Systems and methods for intelligent edge to edge optical system and wavelength provisioning

ABSTRACT

An optical access network includes an optical hub having at least one processor. The network further includes a plurality of optical distribution centers connected to the optical hub by a plurality of optical fiber segments, respectively, and a plurality of geographic fiber node serving areas. Each fiber node serving area of the plurality of fiber node serving areas includes at least one optical distribution center of the plurality of optical distribution centers. The network further includes a plurality of end points. Each end point of the plurality of end points is in operable communication with at least one optical distribution center. The network further includes a point-to-point network provisioning system configured to (i) evaluate each potential communication path over the plurality of optical fiber segments between a first end point and a second end point, and (ii) select an optimum fiber path based on predetermined path selection criteria.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/878,258, filed Jan. 23, 2018. U.S. patent application Ser. No.15/878,258 is a continuation in part of U.S. patent application Ser. No.15/590,464, filed May 9, 2017, and issued as U.S. Pat. No. 10,200,123 onFeb. 5, 2019. U.S. patent application Ser. No. 15/590,464 claims thebenefit of and priority to U.S. Provisional Patent Application Ser. No.62/352,279, filed Jun. 20, 2016. U.S. patent application Ser. No.15/878,258 also claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/449,397, filed Jan. 23, 2017. The disclosures ofall of these prior applications are incorporated herein by reference intheir entireties.

BACKGROUND

The field of the disclosure relates generally to fiber communicationnetworks, and more particularly, to optical access networks utilizingwavelength division multiplexing.

Telecommunications networks include an access network through which enduser subscribers connect to a service provider. Some such networksutilize fiber-optic distribution infrastructures, which havehistorically provided sufficient availability of fiber strands such thatdissimilar types of optical transport signals are carried over their owndifferent fibers. Bandwidth requirements for delivering high-speed dataand video services through the access network, however, is rapidlyincreasing to meet growing consumer demands. As this signal capacitydemand continues to grow, the capacity of individual long access fiberstrands is limited. The cost of installing new long access fibers isexpensive, and dissimilar optical transport signals, unless they arepurposely isolated, experience interference from one another on the samefiber strand. This legacy fiber environment requires operators tosqueeze more capacity out of the existing fiber infrastructure to avoidcosts associated with having to retrench new fiber installment.

Conventional access networks typically include six fibers per node,servicing as many as 500 end users, such as home subscribers, with twoof the fibers being used for downstream and upstream residentialtransport, and the remaining used for node splitting or businessesservices. Conventional nodes cannot be split further using conventionaltechniques, and do not typically contain spare (unused) fibers, and thusthere is a need to utilize the limited fiber availability in a moreefficient and cost-effective manner. Dense Wavelength DivisionMultiplexing (DWDM) environments, for example, are capable ofmultiplexing signals using similar optical transport techniques. Incertain access network environments such as the cable televisionenvironment, DWDM is able to utilize different formats, but its fiberstrand availability is still limited by conventional fiber-opticinfrastructure costs and considerations. Cable access networks includeanalog modulation of the cable RF spectrum onto optical carriers,baseband digital modulation of an optical carrier supporting businessservices, and Ethernet passive optical network (EPON) and Gigabitpassive optical network (GPON) systems carrying data for residential orbusiness subscribers. Each of these different optical transport signalstypically requires its own dedicated long fiber strands.

Coherent technology has been proposed as one solution to meet the everincreasing signal traffic demand for WDM-PON optical access networks, inboth brown and green field deployments, particularly with respect tolong and metropolitan links for achieving high spectral efficiency (SE)and higher data rates per channel. Coherent technology in long opticalsystems typically requires significant use of high quality discretephotonic and electronic components throughout the access network, suchas digital-to-analog converters (DAC), analog-to-digital converters(ADC), and digital signal processing (DSP) circuitry such as anapplication-specific integrated circuit (ASIC) utilizing CMOStechnology, to compensate for noise, drift, and other factors affectingthe transmitted channel signals over the access network. Furthermore, asthe number of end users per optical fiber increases, so does the cost,and power requirements, of implementing all of these electroniccomponents for each terminal device in the network. Some known proposedcoherent solutions have also required their own dedicated long fiberstrands to avoid interference from dissimilar optical transport signals.Accordingly, a solution is desired that allows dissimilar transportsignals to coexist on the same transmission fibers.

BRIEF SUMMARY

In an embodiment, an optical network communication system includes anoptical hub, an optical distribution center, at least one fiber segment,and at least two end users. The optical hub includes an intelligentconfiguration unit configured to monitor and multiplex at least twodifferent optical signals into a single multiplexed heterogeneoussignal. The optical distribution center is configured to individuallyseparate the least two different optical signals from the multiplexedheterogeneous signal. The at least one fiber segment connects theoptical hub and the optical distribution center, and is configured toreceive the multiplexed heterogeneous signal from the optical hub anddistribute the multiplexed heterogeneous signal to the opticaldistribution center. The at least two end users each include adownstream receiver configured to receive one of the respectiveseparated optical signals from the optical distribution center.

In an embodiment, a method of distributing heterogeneous wavelengthsignals over a fiber segment of an optical network is provided. Themethod includes the steps of monitoring at least two different opticalcarriers from at least two different transmitters, respectively,analyzing one or more characteristics of the fiber segment, determiningone or more parameters of the at least two different optical carriers,and assigning a wavelength spectrum to each of the at least twodifferent optical carriers according to the one or more analyzed fibersegment characteristics and the one or more determined optical carrierparameters.

In an embodiment, an optical distribution center apparatus, includes aninput optical interface for communication with an optical hub, an outputoptical interface for communication with one or more end user devicesconfigured to process optical signals, a wavelength filter forseparating a downstream heterogeneous optical signal from the inputoptical interface into a plurality of downstream homogenous opticalsignals, and a downstream optical switch for distributing the pluralityof downstream homogeneous optical signals from the wavelength filter tothe output optical interface in response to a first control signal fromthe optical hub.

In an embodiment, an optical access network includes an optical hubhaving at least one processor. The network further includes a pluralityof optical distribution centers connected to the optical hub by aplurality of optical fiber segments, respectively, and a plurality ofgeographic fiber node serving areas. Each fiber node serving area of theplurality of fiber node serving areas includes at least one opticaldistribution center of the plurality of optical distribution centers.The network further includes a plurality of end points. Each end pointof the plurality of end points is in operable communication with atleast one optical distribution center. The network further includes apoint-to-point network provisioning system configured to (i) evaluateeach potential communication path over the plurality of optical fibersegments between a first end point and a second end point, and (ii)select an optimum fiber path based on predetermined path selectioncriteria.

In an embodiment, a method of provisioning point-to-point communicationsbetween two end points of a multi-end point optical network is provided.The method includes steps of indexing all end points of the opticalnetwork, defining each potential point-to-point connection between theindexed end points, and determining a topological fiber path for eachdefined point-to-point connection. Each topological fiber path includesone or more optical fiber segments. The method further includes steps ofcalculating available transmission wavelengths for each of the one ormore fiber segments, selecting an optimum fiber path between the two endpoints based on the determined topological fiber path and the calculatedavailable transmission wavelengths, and provisioning a point-to-pointcommunication link between the two end points along the selected optimumfiber path.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIGS. 1A-1C illustrate input signal emission spectra that can beutilized with fiber communication systems in accordance with anexemplary embodiment of the present disclosure.

FIGS. 2A-2C illustrate interaction of multiple signals from differentlongitudinal modes according to the exemplary emission spectrum depictedin FIG. 1C.

FIG. 3 is a schematic illustration of an exemplary fiber communicationsystem in accordance with an embodiment of the present disclosure.

FIG. 4 is a schematic illustration of an exemplary fiber communicationsystem in accordance with an embodiment of the present disclosure.

FIG. 5 is a schematic illustration of an alternative fiber communicationsystem to the embodiment depicted in FIG. 4.

FIGS. 6A-6D illustrate an exemplary successive wavelength placement ofheterogeneous optical signals in accordance with an exemplary embodimentof the present disclosure.

FIG. 7 illustrates an alternative three dimensional wavelength placementof the embodiment depicted in FIG. 6D.

FIG. 8 is a flow chart diagram of an exemplary optical signal wavelengthallocation process.

FIG. 9 is a flow chart diagram of an exemplary fiber segment analysisprocess that can be implemented with the allocation process depicted inFIG. 8.

FIGS. 10A-C illustrate is a flow chart diagram of an exemplary signalanalysis process that can be implemented with the allocation processdepicted in FIG. 8.

FIG. 11 is a flow chart diagram of an exemplary spectrum assignmentprocess that can be implemented with the allocation process depicted inFIG. 8.

FIG. 12 illustrates an alternative hybrid optical distribution centerthat can be implemented with the fiber communication systems depicted inFIGS. 3-5.

FIGS. 13A-B illustrate point-to-point optical connections between twoend points and five end points, respectively, in accordance with anembodiment.

FIG. 14 is a schematic illustration of an exemplary architecture for anend-to-end fiber infrastructure, in accordance with an embodiment.

FIG. 15 is a schematic illustration of an exemplary hub and fiber accessdistribution network, in accordance with an embodiment.

FIGS. 16A-B illustrate sectional views of an exemplary fiber sheath andfiber conduit, respectively, in accordance with an embodiment.

FIG. 17 illustrates an exemplary channel map of a portion of the C-Bandand L-band, in accordance with an embodiment.

FIG. 18 is a schematic illustration of an exemplary topology of acable-based end-to-end fiber infrastructure, in accordance with anembodiment.

FIG. 19 is a block diagram of an exemplary sequence of componentstraversed by optical signals, in accordance with an embodiment.

FIG. 20 is a graphical illustration depicting an exemplary powermanagement distribution, in accordance with an embodiment.

FIG. 21 illustrates an exemplary point-to-point network provisioningprocess, in accordance with an embodiment.

FIG. 22 is a flow chart diagram of an exemplary wavelength and fiberpath subprocess that may be implemented with the provisioning processdepicted in FIG. 22.

FIG. 23 is a flow chart diagram of an exemplary cost subprocess that maybe implemented with the provisioning process depicted in FIG. 22 and thewavelength and fiber path subprocess depicted in FIG. 23.

Unless otherwise indicated, the drawings provided herein are meant toillustrate features of embodiments of this disclosure. These featuresare believed to be applicable in a wide variety of systems including oneor more embodiments of this disclosure. As such, the drawings are notmeant to include all conventional features known by those of ordinaryskill in the art to be required for the practice of the embodimentsdisclosed herein.

DETAILED DESCRIPTION

In the following specification and the claims, reference will be made toa number of terms, which shall be defined to have the followingmeanings.

The singular forms “a,” “an,” and “the” include plural references unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” “approximately,” and “substantially,” are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged; such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.

According to the embodiments herein, an optical distribution system iscapable of optimally carrying and multiplexing a plurality ofheterogeneous optical transport signals. The present embodiments mayfurther be advantageously implemented with both new and legacydistribution networks so significantly improve both capacity andperformance of such systems.

Optical signals consume different amounts of fiber resources dependingon their respective power levels, modulation formats, and wavelengththey occupy in relation to wavelengths and characteristics ofneighboring signals, symbols and/or bandwidths, among other parameters.The systems described herein implement hardware and algorithms toaggregate and configure multiple different optical signals within thesame optical fiber. The embodiments herein further utilize disclosurealso introduces relations between performance metrics, optical signalconfiguration parameters and fiber capability for carrying these opticalsignals.

FIGS. 1A-1C illustrate approximate signal emission spectra that can beutilized with fiber communication systems in accordance with anexemplary embodiment of the present disclosure. Referring now to FIG.1A, an emission spectrum 100 for an LED (Light Emitting Diode, notshown) is illustrated. Emission spectrum 100 represents power 102(y-axis) against wavelength 104 (x-axis) for emitted light 106. Laserdiodes are implemented from a semiconductor junction operated in forwardbias mode. Electrons in that junction transition from a higher to alower energy state. In such a process, a photon that has an energy equalto the difference in energy states of the electron is emitted, whichrepresents the spontaneous emission of light present in an LED, asillustrated in FIG. 1A.

Referring now to FIG. 1B, an emission spectrum 108 is illustrated for alaser diode such as a Fabry Perot laser diode (FPLD) or avertical-cavity surface-emitting laser (VCSEL). Such laser diodes mayalso implement reflective facets or mirrors so that generated photonsbounce back and forth stimulating, along their path, the emission ofmore photons. This stimulated emission, or lasing, results in lightemission at higher intensity levels and with a high degree of coherence.The mirror or facets on opposite sides of the active region formed bythe junction create an optical cavity. The geometry of that cavity alongwith the range in energy levels generated by the change of state in thejunction will determine one or more dominant resonant wavelengthstransmitted by the laser diode.

In an exemplary embodiment, an FPLD may have an optical bandwidth of 5to 10 nanometers (nm), and generate a plurality of individuallongitudinal modes 110, each having an output bandwidth typically lessthan 2 nm. In an embodiment, an 850 nm laser diode with a length ofaround 300 micrometers (μm) and a refractive index of approximately 4may have a longitudinal mode spacing of 0.3 nm, which is similar to a 1mm long 1550 nm laser diode. Changing the length or refractive index ofthe cavity, for example by heating or cooling the laser diode, may shiftthe whole comb of modes and consequently the output wavelength.

Referring now to FIG. 1C, an emission spectrum 112 is illustrated for alaser diode such as a distributed feedback laser diode (DFBLD). In anoptical signal source, the dominant lasing wavelength is dependent onthe material which provides a broad wavelength range that generateslight based on the band-gap between electron states of a semiconductorjunction, as well as the length of the cavity which results in amultitude of resonant modes that restricts the wavelengths. The dominantlasing wavelength is further dependent on structural characteristics ofthe cavity that further restrict resonance to a single longitudinal mode114, while suppressing adjacent longitudinal modes 116. A DFBLD, througha periodic index of refraction variation, is capable of thus limitingresonance substantially to a single wavelength, i.e., longitudinal mode114, as illustrated in FIG. 1C.

According to the embodiments described herein, and further below,sources include LEDs, FPLDs, VCSELs, and DFBLDs. One of ordinary skillin the art though, after reading and comprehending the presentdisclosure, will understand that other sources may be implementedwithout departing from the scope of the application. The sourcesdescribed herein are capable of converting electrical signals intooptical signals, and can be significantly different devicesstructurally. In an exemplary embodiment, the lasing source can bemanufactured on semiconductor devices/chips. LEDs and VCSELs, forexample, may be fabricated on semiconductor wafers such that light isemitted from the surface of the chip. FPLDs may be fabricated such thatlight is emitted from the side of the chip from a laser cavity createdin the middle of the chip.

LEDs are the least expensive source, but produce lower power outputsthan most of the other optical sources. LEDs also produce a larger,diverging light output pattern (see FIG. 1A, above), which reduces theapplications available to couple LEDs into fibers. LEDs and VCSELsthough, are generally inexpensive to manufacture in comparison with theother sources described herein. FPLDs and DFBLDs, for example, are moreexpensive to manufacture due to the necessity of creating the lasercavity inside the device, however, the output light from such sourcesare narrower and more easily coupled to single mode fibers.

DFBLDs have narrower spectral width than FPLDs, which realizes lesschromatic dispersion on longer fiber links. DFBLDs are more expensive tomanufacture than FPLDs, but also produce a more highly linear output,that is, the light output directly follows the electrical input, and maybe preferable as sources in AM CATV systems and long distance and DWDMsystems. According to the embodiments described below, many of thesesources can be utilized alternatively and/or together according to theadvantageous structural configurations described below.

FIGS. 2A-2C illustrate interaction of multiple signals from differentlongitudinal modes according to the exemplary emission spectrum depictedin FIG. 1C. In a fiber optic distribution system, there are manypotential sources for non-linear behavior. One known source ofnon-linear behavior is an optical amplifier, such as an erbium-dopedfiber amplifier (EDFA). However, even when no amplifiers are present,fiber non-linearities can also impact performance, such as fromcross-phase modulation (CPM), self-phase modulation (SPM), and/orfour-wave mixing (FWM) which originate when the index of refractionchanges with optical power.

Referring now to FIG. 2A, an emission spectrum 200 is illustrated for afirst signal source (not shown) generating a first dominant longitudinalmode 202, and suppressing first adjacent longitudinal modes 204. FIG.2B, illustrates an emission spectrum 206 is illustrated for a secondsignal source (not shown) generating a second dominant longitudinal mode208, and suppressing second adjacent longitudinal modes 210. In anexemplary embodiment, first and second signal sources are heterogeneouswith respect to one another. FIG. 2C represents the superpositionemission spectrum 212 of first and second signal sources together.

Referring now to FIG. 2C, one type of a non-linear effect is illustratedto depict intermodulation between adjacent carriers. In this example,first dominant longitudinal mode 202 and second dominant longitudinalmode 208, along with their respective suppressed first adjacentlongitudinal modes 204 and second adjacent longitudinal modes 210, arespaced apart along the wavelength spectrum, such as may occur with firstand second signals are intermodulated over the same fiber. In thisexample, the simultaneous transmission of the two signals on the samefiber produces noise artifacts 214 within the spectra of adjacentlongitudinal modes 204, 210. Noise artifacts 214(1) and 214(2) includenon-linear components resulting from the interference of the first andsecond signals. Noise artifacts 214 are more difficult to manage wherethe first and second signals are heterogeneous and not filtered.

Additionally, as different parameters, such as temperature, current,modulation bandwidth, and others change, the lasing wavelength of therespective signal may shift, or a different lasing mode may becomedominant, thereby further increasing the likelihood and significance ofnoise artifacts 214 in operation. For these reasons, conventionalsystems do not transmit heterogeneous signals over the same fibers.According to the systems and methods disclosed herein, on the otherhand, a plurality of heterogeneous optical signals, carried overdifferent wavelengths, are transmitted through a single fiber, bymanaging and mitigating the interference problems that would beotherwise experienced by conventional communication networks.

FIG. 3 is a schematic illustration of an exemplary fiber communicationsystem 300 implementing the principles described above with respect toFIGS. 1 and 2. System 300 includes an optical hub 302, an opticaldistribution center (ODC) 304, deep nodes 306, and end users 308. Endusers 308 are one or more downstream termination units, which can be,for example, a customer device or customer premises 308(1) (e.g., ahome, apartment building, or residential radio frequency over glass(RFoG) subscribers), a business user 308(2) (including point tomultipoint fiber networks with business EPON subscribers), an opticalnetwork unit (ONU, not shown), or a cellular base station 308(3)(including small cell base stations). Optical hub 302 is, for example, acentral office, a communications hub, or an optical line terminal (OLT).In an exemplary embodiment, system 100 utilizes a passive opticalnetwork (PON) and coherent Dense Wavelength Division Multiplexing (DWDM)PON architecture. ODC 304 may be separate from deep nodes 306, or mayinclude a hybrid architecture (see FIG. 12) that includes at least onedeep node within the same ODC apparatus structure.

Optical hub 302 communicates with optical distribution center 304 by wayof long fiber 310. In an exemplary embodiment, long fiber 310 istypically around 30 kilometers (km) in length, but may vary, asdescribed below. However, according to the embodiments presented herein,greater lengths are contemplated, such as between 100 km and 300 km, andup to 1000 km. Optionally, long fiber 310 may be two separate fibersseparately dedicated to downstream and upstream communication,respectively.

In an exemplary embodiment, optical distribution center 304 connectswith end users 308 directly through short fibers 312, coaxial cable 314,and/or indirectly through intervening deep nodes 306. Signal power overcoaxial cable 314 may be boosted by amplifiers 316 located along thecable path. In an exemplary embodiment, an individual short fiber 312spans a distance typically less than 5000 feet.

In this example, fiber communication system 300 represents a cableaccess network, which may span distances ranging from 5 km to 140 km.Over this range, signal behaviors that depend on the time of interaction(common distance) are a consideration. Such behaviors may include fibernon-linear effects, dispersion, among others. Typical access networksmay split a single fiber into many subpaths, which can result in asignificant power loss (e.g., up to 18 decibel (dB) loss for a 32-waysplit) along the subpaths. The low robustness signal characteristic canfurther render some signal types more susceptible to noise generated byadjacent signals, as well as optical carriers exhibiting higher power.

To address these issues, optical hub 302 further includes an intelligentconfiguration unit 318 and at least one transmitter 320. Optionally,where upstream communication is desired, optical hub 302 furtherincludes at least one receiver 322. Intelligent configuration unit 318further includes a processor 324 and a signal multiplexer 326. Asdescribed further below with respect to FIGS. 6-11, processor 324functions to analyze and aggregate a plurality of heterogeneous opticalsignals along an optimum spectrum distribution for transmission bymultiplexer 326 over the same long fiber 310.

Intelligent configuration unit 318 operates to analyze (i.e., byprocessor 324) and aggregate (i.e., by multiplexer 326) a plurality ofheterogeneous signals by measuring and controlling one or more of thefollowing parameters: signal wavelength; optical power; modulationformat; modulation bandwidth; polarization multiplexing; channelcoding/decoding, including forward error correction, and fiber length.Intelligent configuration unit 318 is thus able to maximize the capacityof long fiber 310 to transmit multiple heterogeneous signals to ODC 304,where the multiplexed heterogeneous signals can be demultiplexed andseparately transmitted to individual hybrid fiber-coaxial (HFC) opticalnodes, such as deep nodes 306, to an expanding number of end pointswithin the existing HFC node serving area of system 300. In an exemplaryembodiment, these end points may include additional deep nodes 306 insuccession, or cascade, along particular additional signal transmissionpaths that have been generated through successive node splitting inresponse to capacity shortage.

According to the embodiments herein, optical transmission ofheterogeneous signals over existing optical fiber networks significantlyimproves the capacity of existing fibers that only transmit a singleoptical signal. Optical fibers that carry only one optical signal havefew parameters to consider in optimizing performance for that particulartransmission, since there is generally no interaction with other opticalsignals. For single optical signal transmission, considerations forperformance optimization are dependent only on the limitations that thesignal generates onto itself, as well as linear and non-linear factorsof the optical transmission medium.

The simultaneous transmission of multiple heterogeneous optical signals,on the other hand, addresses a variety of different modulation formatsand configuration parameters among the several signals. The presentoptimization scheme additionally selects configuration parameters basedon the performance dependencies that exist between the different opticalsignals, as well as the fiber medium they share.

Intelligent configuration unit 318 functions to multiplex a plurality ofheterogeneous optical signals together according to specific criteria tooptimize quality of signal transmission while minimizing interferencebetween optical signals of different types. Intelligent configurationunit 318 analyzes incoming optical signals of different types (e.g.,analog, direct, coherent, etc.) using processor 324, and multiplexes thesignals together utilizing signal multiplexer 326 so that the differentsignals may coexist over the length of long fiber 310 withoutsubstantially interfering with each other. Intelligent configurationunit 318 works cooperatively with ODC 304 such that ODC 304 maydemultiplex the heterogeneous signal types from one another to beseparately transmitted over short fibers 312 to particular end users 308capable of receiving that type of signal, as illustrated below withrespect to FIGS. 4 and 5.

In an exemplary embodiment, ODC 304 functions as a one-stage opticalfilter to separate the input multiplexed heterogeneous signals fromintelligent configuration unit 318, over long fiber 310, into outputseparate homogeneous signal types over short fibers 312. In thisembodiment, ODC 304 performs as a pure optical-in/optical-out filter. Inan alternative embodiment, ODC 304 is additionally capable of convertingone or more output homogeneous signals into an electrical signaltransmitted over cable 314. Where deep nodes 306 are implemented alongthe signal path, a homogenous signal of a particular carrier type can befiltered by a particular deep node 306 to output a particular bandwidthfor continued transmission to a particular end user 308. Alternatively,fiber deployed from ODC 304 may include direct express fiber runs toeach, or some, of end users 308.

ODC 304 and cascading deep nodes 306 thus a function together as aflexible spectrum filter, with deep nodes 306 tailored to the particularbandwidth desired. In contrast, conventional filtering techniques areknown to drop or add wavelengths onto a fiber loop. The wavelength- andfiber-sharing techniques disclosed herein may thus result incost-effective implementations to reach the end user. Variations andevolved implementations of EPON and GPON systems are also compatiblewith the systems and methods disclosed herein. By this advantageousconfiguration, multiple signals different carrier types effectively“re-use” the same long fiber that would be conventionally dedicated toonly one single signal type, thus eliminating the need to retrench newfibers for the different signal types.

FIGS. 4 and 5 illustrate alternative system implementations to employthe principles described above with respect to FIG. 3. The alternativesystem implementations both are configured to aggregate heterogeneousoptical signals within at least one long fiber each for downstream andupstream transmission, thereby leveraging the fibers presently availablein the optical access environment of cable networks. If more efficientfiber utilization is desired, downstream and upstream transmissions maybe both placed on a single fiber, through utilization of the wavelengthcontrol and management capabilities of intelligent configuration unit318. However, in such instances, the amount of wavelength spectrum perdirection (upstream or downstream) would be reduced in half. In anexemplary embodiment, optical circulators are employed at both ends ofthe fiber link (e.g., systems 300, 400, 500) to further enable thisbidirectional alternative approach over a single fiber. Accordingly,both alternative systems shown in FIGS. 4 and 5, respectively, may bemaintained such that they are kept substantially free of optical beatinterference (OBI free).

In the exemplary alternatives shown in FIGS. 4 and 5, both systems areillustrated to implement cable fiber distribution networks.Nevertheless, a person of ordinary skill in the art, after reading andcomprehending the written description herein and its accompanyingdrawings, will understand to be able to apply the principles andtechniques so disclosed to other types of optical distribution networks,such as cellular distribution networks, digital subscriber line (DSL)based distribution networks, and others.

Referring now to FIG. 4, a schematic illustration of an exemplary fibercommunication system 400 is shown. System 400 is capable of leveragingwavelength tuning capabilities of multiple optical sources. Similar tosystem 300, above, system 400 includes an optical hub 402, an ODC 404,and end users 406. Optical hub 402 communicates with ODC 404 throughdownstream long fiber 408 and optional upstream long fiber 410. ODC 404communicates with end users 406 through short fibers 412. Forsimplification of explanation, deep nodes and cable are not shown, butmay be implemented along the signal path of short fibers 412 in asimilar manner to the embodiments described above with respect to FIG.3.

Optical hub 402 includes a downstream transmitting portion 414 and anoptional upstream receiving portion 416. In an exemplary embodiment,downstream transmitting portion 414 includes at least two of an analogdownstream transmitter 418, an intensity modulated direct detection(IM-DD) downstream transmitter 420, and a coherent downstreamtransmitter 422. End users 406 are comparable to end users 308 (FIG. 3),and may, for example, include one or more downstream termination units.In the exemplary embodiment, end users 406 include at least two of ananalog downstream receiver 424, an IM-DD downstream receiver 426, and acoherent downstream receiver 428.

Where upstream communication is optionally desired (i.e., throughupstream long fiber 410), upstream receiving portion 416 includes atleast two of an analog upstream receiver 430, an IM-DD upstream receiver432, and a coherent upstream receiver 434. In this exemplary embodiment,end users 406 include at least two of an analog upstream transmitter436, an IM-DD upstream transmitter 438, and a coherent upstreamtransmitter 440.

In operation, optical hub 402 further includes an intelligentconfiguration unit 442, comparable to intelligent configuration unit 318(FIG. 3), which analyzes incoming optical signals 444 of different types(e.g., analog optical signal 444(1), IM-DD optical signal 444(2),coherent optical signal 444(3), etc.) and multiplexes the incomingoptical signals 444 together so that the different signals may coexistover the length of long fiber 408 without substantially interfering witheach other. Intelligent configuration unit 442 works cooperatively withODC 404 such that ODC 404 may demultiplex the heterogeneous signal typesfrom one another to be separately transmitted over short fibers 412 toparticular end users 406 capable of receiving that type of signal. Forexample, analog optical signal 444(1) is received by analog downstreamreceiver 424 of end user 406(1), IM-DD optical signal 444(2) is receivedby IM-DD downstream receiver 426 of end user 406(2), and coherentoptical signal 444(3) is received by coherent downstream receiver 428 ofend user 406(3).

In the exemplary embodiment, intelligent configuration unit 442 is asingle intelligent device that also functions to multiplex, aggregate,and combine incoming optical signals 444. In an alternative embodiment,the multiplexing, aggregating, and combining functions may be performedby separate, passive devices (not shown). According to anotheralternative, such separate devices include sufficient intelligencefunctionality such that they are subject to some level of control andmanagement by intelligent configuration unit 446. In some embodiments,intelligent configuration unit 446 is a standalone device that managesand controls separate devices that function to monitor and manipulatesignals, including, for example, lasers that can be configured to usedspecific channels and operate with certain conditions to coexist and/orimprove system performance. Some of such separate devices may becontrolled directly by intelligent configuration unit 446, which, inthis example, further includes control and communication interfaces (notshown) to extract and send information to the separate devices thatenable the direct manipulation of incoming optical signals 444. Suchseparate devices are alternatively controlled by indirect communicationwith intelligent configuration unit 444, for example, through a controlchannel (not shown). In some embodiments, intelligent configuration unit446 is combined with separate multiplexers, aggregators, and/orcombiners in an integrated structure.

In an exemplary embodiment, ODC 404 includes a wavelength filter 446,which is implemented for downstream transmission to efficientlytransition from the single fiber-multiple wavelength medium (i.e.,downstream long fiber 408) between optical hub 402 and ODC 404, to themultiple fiber/single wavelength per fiber environment (i.e., shortfibers 412) between ODC 404 and the respective termination devices ofend users 406. Wavelength filter 446 may include, for example, awavelength-division multiplexing (WDM) grating, and/or a cyclic arrayedwaveguide grating (AWG). In the exemplary embodiment, ODC 404 furtherincludes a downstream optical switch 448, which utilizes a controlsignal from intelligent configuration unit 442 to transmit the outputfrom wavelength filter 446 along downstream short fibers 412. Whereupstream transmission is optionally desired, ODC 404 further includes anoptical combiner 450 to aggregate signals from the many upstream shortfibers coming from the optical end devices of end users 406, to a singlefiber (i.e., upstream long fiber 410) at ODC 404. Optical combiner 450may include a WDM grating or splitter. In this configuration, ODC 404further may include an upstream optical switch 452 between short fibers412 and optical combiner 450, which together function to combine thedifferent upstream optical carrier into a single upstream heterogeneouswavelength multiplexed signal, in coordination with the wavelengthspacing and tuning processes of intelligent configuration unit 442,described further below. This aggregate upstream heterogeneous signal iscarried over upstream long fiber 410 from ODC 404 to optical hub 402.

In an exemplary embodiment, data streams within optical hub 402 areassociated for the purpose of reception/transmission from/to thedifferent optical downstream transmitters 418, 420, 422 and upstreamreceivers 430, 432, 434, which are in communication with or connected tospecific ODCs throughout the area optical hub 402 serves (see also FIG.3, above). In this embodiment, intelligent configuration unit 442 isconfigured to utilize the known capability and configuration ofwavelength filter 446 (WDM grating or demultiplexer) to furtherconfigure optical signal parameters, such as wavelength, bandwidth,modulation type, etc., of downstream transmitters 418, 420, 422, inorder to reach specific target subscribers (i.e., end users 406).

In an alternative embodiment, downstream optical switch 448 isoptionally an N×N optical switch, and intelligent configuration unit 442is further configured to transmit control messages to downstream opticalswitch 448 to associate specific ports (not shown) with specificperformance characteristics and signal types to target subscribers,thereby providing significant flexibility in the type of service andwavelength system 400 can dedicate to a particular target subscriber. Inan alternative embodiment, where cost considerations are of greaterconcern, the N×N switch may be sized such that it covers only particularsubscribers (e.g., a business) that require greater flexibility inadjusting parameters. Residential subscribers, for example, may be fixedto a specific wavelength assignment and service configuration.

In this embodiment, for the reverse transmission direction, upstreamsignal flow is controlled by intelligent configuration unit 442 so thatthe appropriate wavelength is routed to the appropriate receiver type(e.g., upstream receivers 430, 432, 434) in optical hub 402. Incontrast, conventional optical nodes each serve only one signal type,and may not further function to manipulating or route signal trafficbased on wavelength or signal type. For such conventional nodes, thecharacteristics of the transmitted signal are typically fixed based onthe intended service. Accordingly, the signal processing in the upstreamdirection is substantially equivalent to the signal processing in thedownstream direction, but in reverse. For example, for each command ODC402 receives from intelligent configuration unit 442 for downstreamtransmission, intelligent configuration unit 442 may generate acounterpart command intended for upstream transmission. In an optionalembodiment, upstream transmission aggregates channels utilizing apassive combiner (not shown) instead of a wavelength multiplexer.

In an exemplary embodiment, fiber communication system 400 may befurther configured to include and implement an optical frequency combgenerator (not shown) for generating at least one coherent tone pair foreach coherent optical signals 444(3), which is then multiplexed withinintelligent configuration unit 442, or by a separate device (describedabove) in communication with intelligent configuration unit 442, priorto transmission over downstream long fiber 408 to ODC 404. Thisexemplary architecture and processing are described in greater detail inco-pending U.S. patent application Ser. No. 15/283,632, filed Oct. 3,2016, which is incorporated by reference herein.

Implementation of the embodiments described herein is useful formigrating hybrid fiber-coaxial (HFC) architectures towards other typesof fiber architectures, as well as deeper fiber architectures. TypicalHFC architectures tend to have very few fiber strands available from ODCto hub (e.g. fibers 408, 410), but many fiber strands could be deployedto cover the shorter distances that are typical from legacy HFC nodes toend users (e.g., fiber optics 412). In the exemplary embodimentsdescribed herein, two fibers (i.e., fibers 408, 410) are illustratedbetween optical hub 402 and ODC 404, which can include one or morelegacy HFC fiber nodes. That is, one fiber (i.e., downstream fiber 408)is utilized for downstream signal, and another fiber (i.e., upstreamfiber 410) is utilized for upstream signal. By utilization of theadvantageous configurations herein, fiber deeper or all-fiber migrationschemes can greatly minimize the need for fiber retrenching from an ODCor an HFC node to an optical hub. As described above, although twofibers (i.e., fibers 408, 410) are illustrated in FIG. 4, the presentsystems and methods may also be implemented utilizing only a singlefiber, with the utilization of additional optical circulators andwavelength management, for example as described further below.

Whereas the conventional fiber access network architecture transmitsonly analog signals through the conventional mode, the advantageousarchitecture disclosed herein, through implementation of an intelligentconfiguration unit and an ODC, is capable of additionally transmittingdirect and coherent optical signals simultaneously over the same longfiber based on available signal bandwidth occupancy, as disclosedfurther below with respect to FIGS. 6-10. This novel architecture andprocessing method is therefore particularly optimized for a cableenvironment desiring to reuse long fibers from a hub to a node. Theembodiments described herein may also be adapted to a remote PHYsolution, a remote cable modem termination system (CMTS) that isincluded in the fiber node, a coherent and non-coherent DWDM-PONarchitecture, a non-coherent IM-DD architecture, and/or intradyne,homodyne, and heterodyne coherent detection schemes in a long system.

In an exemplary embodiment, fiber communication system 400 is configuredto further implement wavelength tuning and selectable fixed wavelengths.Specifically, the various optical sources that become optical signals444 will optimally have either the capability of wavelength tuning, orfor fixed optical wavelength sources, the sources can be selected suchthat the sources may be implemented according to the allocation andoptimization criteria described herein. As discussed above, conventionalnetworks typically have few spare fibers between the optical hub and thelegacy node. Accordingly, one fiber is presumed to be available fortransmission in the downstream direction, and one fiber is presumed tobe available in the upstream direction, both typically covering tens ofkilometers distance from hub to node. The requirement to use only asingle fiber for each of downstream and upstream transmission does notpermit fiber retrenching between the hub and the node. According to thenovel systems and methods disclosed herein, however, new fiberinstallation need only be implemented over the significantly shorterdistances (e.g., short fibers 412) between the ODC, legacy HFC fibernodes, deeper nodes, end devices at businesses, and/or base stations orhomes (in case of fiber to the home architectures). Such new fiberextensions would typically span no more than a few thousand meters.According to this novel architecture, a legacy HFC fiber node can beeffectively converted into an ODC where many fiber segments originatetowards these new optical termination devices or optical end devices.

In an exemplary embodiment, the access network fiber topology of system400 implements signals from sources including, without limitation:analog modulated optical carriers such as the subcarrier multiplexedchannels used in cable; baseband digital modulated signals using directdetection mechanisms such as non-return-to-zero (NRZ), return-to-zero(RZ), pulse amplitude modulation (PAM), including PAM4 and PAM8;differential detection signals such as differential phase-shift keying(DPSK) and differential quadrature phase-shift keying (D-QPSK); coherentmodulated optical signals such as binary phase-shift keying (BPSK),quadrature phase-shift keying (QPSK) and higher order quadratureamplitude modulation (QAM); and polarization multiplexing transmissiontechniques for coherent modulation.

In further operation within the environment of fiber communicationsystem 400, wavelengths of respective components are subject to changeunder different conditions. In some situations, where any two signalwavelengths get close enough to each other, a level of interferencebetween the respective signals may increase. Where two such signalwavelengths lay on top of each other, optical beat interference may alsobe experienced. In an exemplary embodiment, laser diodes may beimplemented, which are configured to have temperature control and/orfrequency tuning control (T/F Ctrl) capabilities to maintain signalwavelengths such that they may be separated at specific desired spacingwithin certain tolerance values. According to an exemplary embodiment offiber communication system 400, at least one laser diode is implementedfor each respective transmitter and receiver within the network. In anembodiment, at least two long fibers (e.g., long fibers 408, 410) arerequired for N subscribers (e.g., end users 406) using N wavelengths.Alternatively, a single fiber could be used for N subscribers using 2Nwavelengths, that is, N downstream wavelengths and N upstreamwavelengths.

FIG. 5 is a schematic illustration of an alternative fiber communicationsystem 500. Fiber communication system 500 is similar to fibercommunication systems 300 (FIG. 3) and 400 (FIG. 4), except that fibercommunication system 500 utilizes wavelength filtering and injectionlocking techniques, which are also described in greater detail inco-pending U.S. patent application Ser. No. 15/283,632, as discussedabove. Fiber communication system 500 includes an optical hub 502, anODC 504, and end users 506. Optical hub 502 communicates with ODC 504through downstream long fiber 508 and upstream long fiber 510. ODC 504communicates with end users 506 through short fibers 512. Forsimplification of explanation, deep nodes and cable (e.g., coaxial) arenot shown, but may be implemented along the signal path of short fibers512 similarly to the embodiments described above with respect to FIGS. 3and 4.

Optical hub 502 includes a downstream transmitting portion 514 and anoptional upstream receiving portion 516. In an exemplary embodiment,downstream transmitting portion 514 includes at least two of an analogdownstream transmitter 518, a polarization multiplexed IM-DD downstreamtransmitter 520, and a coherent downstream transmitter 522. End users506 are comparable to end users 308 (FIG. 3) and end users 408 (FIG. 4),and may, for example, include one or more downstream termination units.In the exemplary embodiment, end users 506 include at least two of ananalog downstream receiver 524, a polarization multiplexed IM-DDdownstream receiver 526, and a coherent downstream receiver 528. Whereupstream communication is optionally desired (i.e., through upstreamlong fiber 510), upstream receiving portion 516 includes at least two ofan analog upstream receiver 530, a polarization multiplexed IM-DDupstream receiver 532, and a coherent upstream receiver 534. In thisexemplary embodiment, end users 506 include at least two of an analogupstream transmitter 536, a polarization multiplexed IM-DD upstreamtransmitter 538, and a coherent upstream transmitter 540. A polarizationmultiplexed IM-DD link is illustrated in the exemplary embodiment ofFIG. 5. Nevertheless, the present systems and methods may be implementedutilizing a subset link that is not polarization multiplexed. Theinjection locking techniques described herein advantageously allow forthe novel combination of polarization multiplexing with IM-DD.

In operation, optical hub 502 further includes an intelligentconfiguration unit 542, comparable to intelligent configuration units318 (FIG. 3) and 442 (FIG. 4), and may be a standalone or integrateddevice having multiple functionalities, or a separate device incommunication with other devices serving to multiplex, aggregate, and/orcombine various signals. Intelligent configuration unit 542 workscooperatively with ODC 504 such that ODC 504 may demultiplex theheterogeneous signal types from one another to be separately transmittedover short fibers 512 to particular end users 506 capable of receivingthat type of signal.

In an exemplary embodiment of fiber communication system 500, furtherincludes a seed generator 544 and a wavelength filter 546. Wavelengthfilter 546 may include, for example, a WDM grating. In operation,wavelength filter 546 serves to support injection locking of laserdiodes implemented within the various respective transmitters andreceivers of the network. In an exemplary embodiment, the variousoptical sources represented by transmitters 518, 520, 522 includeinjection locked lasers that are modulated using different formats, andthe master source (not shown) for injection locking is a multi-tonegenerator of high spectral purity (narrow linewidth), as described inco-pending U.S. patent application Ser. No. 15/283,632, discussed above.In an alternative embodiment, other or additional optical sources couldbe implemented, including, but not limited to, broadband wavelengthsources. Implementation of the narrow linewidth source described hereinadvantageously allows for a significantly diversified set of modulationformats, including coherent optical modulation.

According to the embodiment illustrated in FIG. 5, wavelength filtersmay be advantageously implemented to separate multi-tone optical signalsinto individual wavelengths to injection lock the lasers. Additionally,the multi-tone sources may be placed in different locations. In anexemplary embodiment, in order to minimize complexity in thedistribution portion of the network, a multi-tone source is disposed inwithin optical hub 502 near to where the downstream signals originate.In an exemplary embodiment, ODC 504 further includes a demultiplexingwavelength filter 548 and a multiplexing wavelength filter 550. Filter548 may, for example, include a cyclic arrayed waveguide grating (AWG),and filter 550 may, for example, include a WDM grating or splitter.

Similar to the embodiment illustrated in FIG. 4, the access networkfiber topology of fiber communication system 500 implements signals fromsources including, without limitation: analog modulated optical carrierssuch as the subcarrier multiplexed channels used in cable; basebanddigital modulated signals using IM-DD mechanisms such as NRZ, RZ, PAM4,and PAM8; differential detection signals such as DPSK and D-QPSK;coherent modulated optical signals such as BPSK, QPSK, and higher orderQAM; and polarization multiplexing transmission techniques for coherentmodulation and non-coherent modulation, as shown in the IM-DDconfigurations illustrated in FIG. 5.

In an alternative embodiment, fiber communication system 500 is furtherconfigured to implement coherent links by leveraging the high spectralpurity of a common injection locking source (not shown) received by twodifferent lasers, but where one of the round trip paths to a laser isshifted in phase by 90 degrees. This phase shifting generates the I andQ paths needed for a coherent QAM modulated signal using two directlymodulated laser diodes. This technique can be expanded to twopolarizations with 4 directly modulated laser diodes thereby achievingpolarization multiplexing, as described in co-pending U.S. patentapplication Ser. No. 15/283,632, discussed above. In a furtheralternative embodiment, polarization multiplexing may be achievedthrough utilization of at least two direct detect links that share acommon injection locking source. The resulting two injection lockedtransmitters can thus be polarization multiplexed once so synchronizedthrough the common injection locked source. In this embodiment, theintensity modulation of light described here can be achieved throughdirect modulation of laser diode current. However, the present systemsand methods may also utilize other intensity modulation techniques, suchas electro-optical and electro-absorption intensity modulationtechniques using external modulators.

Fiber communication system 500 differs from fiber communication system400 system 500 is advantageously capable of avoiding use of temperaturecontrol or frequency control mechanisms, due to the fact that the novelfiltering techniques of system 500, as well as the generation of equallyspaced multi-tones, serves to restrict lasing to a fixed spacing betweenwavelengths. Systems and methods according to this embodiment furtheradvantageously also results in the elimination of optical beatinterference. System 500 further differs from system 400 in that, wheresystem 400 utilizes two fibers for N subscribers that fully use thefiber spectrum, system 500 utilizes unmodulated optical carriers forinjection locking which use half of a single fiber spectrum. Therefore,in this example, with two fibers available, one half of a one fiberspectrum is used for downstream data, one half of one fiber spectrum isused for upstream data, one half of one fiber spectrum is used forunmodulated optical carriers, and the remaining half of the fiberspectrum of the two fibers is not used. Accordingly, if three fibers areutilized, an entire spectrum of a first fiber may be used for downstreamdata transmission, an entire spectrum of a second fiber may be used forupstream data transmission, and an entire spectrum of the third fibermay be used for unmodulated optical carriers. Thus, to carry N opticalcarriers with the same bandwidth, system 400 would need two opticalfibers, whereas system 500 would need three optical fibers. In thisexample, system 500 is less efficient than system 400; however, thelaser diodes (not numbered) utilized by end users 506 are not requiredto be wavelength-specific, thereby resulting in significantly lowercapital and operating expenditures throughout system 500.

In a further alternative embodiment, the present inventors contemplatehybrid approach to implement principles of systems 400 and 500 together,including, without limitation, a wavelength filtered architecture wheresome of the optical sources are wavelength-tuned or of a fixedwavelength to fit within a filtered channel. In such a hybrid system,the seed optical signal to injection lock the optical transmitter may beavoided for at least a portion of the optical links. In an exemplaryembodiment of this alternative, some optical signals will be capable ofwavelength tuning and others will have fixed wavelengths requiringoperator knowledge of the wavelength and signal format to optimizeperformance, and/or wavelength filtering is implemented utilizinginjection locking techniques.

FIGS. 6A-6D illustrate an exemplary process 600 for successivewavelength placement of heterogeneous optical signals in accordance withan exemplary embodiment of the present disclosure. Process 600implements an intelligent wavelength mapping approach (e.g., by anintelligent configuration unit according to the above-describedembodiments) of optical signals over the wavelength transmission windowof a fiber. In an exemplary embodiment, process 600 includes one or morealgorithms for optical signal wavelength allocation and configurationoptimization, and includes methodology regarding how a fiberinfrastructure is optimized to achieve capacity, robustness, and otherperformance targets based on one or more of optical link resources andcomponent characteristics, optical channel conditions, and thetransmission requirements.

Process 600 provides for one or both of wavelength mapping andwavelength allocation for the different optical links, having differentmodulation formats and detection schemes, to meet traffic servicerequirements of the fiber infrastructure. Process 600 advantageouslyallows an optical hub to significantly increase the volume ofheterogeneous signals that can be transmitted over available fiberspectral resources. Process 600 is organized such that, when implementedby a processor (e.g., processor 324, FIG. 3), an intelligentconfiguration unit is able to gather information on components used,types of optical links, and types and characteristics of thearchitecture within the fiber communication system. For example, process600 is configured to determine whether a particular signal isrepresented by a tunable wavelength, a fixed wavelength, or a filteredwavelength or a hybrid architecture.

In an exemplary embodiment, process 600 is further configured toleverage one or more of the following optical carrierparameters/characteristics: individual carrier power levels; aggregatecarrier power; number of optical carriers; wavelength spacing amongcarriers; modulation format used; carrier configurability; and carriertunability. Process 600 may be further configured to additionally takeinto consideration one or more of the following fiber environmentcharacteristics: type of fiber; amplification and/or loss devices (e.g.,an EDFA); wavelength filters or splitters; and fiber distributionnetwork topology. Additionally, process 600 may still further considerthe measurement and classification of fixed-wavelength andunknown-wavelength laser diodes in order to determine a correctwavelength bin. The size of a wavelength bin, for example, may beaffected by an assessment of temperature, age, or power variability. Inan exemplary embodiment, a wavelength is presumed to stay within adetermined wavelength bin when the wavelength is deemed to becontrollable.

In an optional embodiment of process 600, depending on the modulationformat used, target optical signal to noise ratio (OSNR) requirementsfor different optical signals are calculated in advance and generatedinto a lookup table, which may then be utilized during implementation ofprocess 600 to control and minimize the optical power of each opticalcarrier, and also to adjust optical power of a carrier when noise levelincreases due to non-linear effects/interactions among the severalcarriers. Such non-linear effects may include self-phase modulation(SPM), cross-phase modulation (CPM), and/or four-wave mixing (FWM). Theeffects of SPM and CPM are more pronounced on signals with highermodulation bandwidths. The effects of FWM and CPM are more pronouncedwith narrower/decreased channel spacing of wavelengths. The effects ofFWM are also more pronounced with signals having lower chromaticdispersion. FWM is therefore of particular concern with spread signals.

Furthermore, noise assessment may depend not only on the type of source,but also on whether direct or external modulation is used, as well asany introduction of noise by devices such as amplifiers, such as noisefrom an EDFA, or amplified spontaneous emission(ASE)/superluminescence).

FIG. 6A illustrates a graphical representation of an initial wavelengthplacement according to process 600. According to an exemplaryembodiment, this initial placement is represented by an optical signalintensity 602 (y-axis) over a wavelength spectrum 604 (x-axis) of thefiber for a plurality of analog carrier signals 606(1), . . . 606(N).Placement of analog carrier signals 606 (also referred to as carriers orcarrier waves) may occur, for example, after an initial assessment ofthe optical link resources and characteristics of the network topology.

In the exemplary embodiment, analog carriers 606 are chosen for initialplacement because they represent fixed wavelength optical carriers, andmay include analog modulated links carrying their respective signals athigh power levels due to high signal to noise ratio (SNR) requirements.Analog carrier signals are typically not tunable, but are often thelargest contributors of noise over wavelength spectrum 604. Analogcarrier signals include high linearity requirements, and are consideredto be less flexible than other signals. Analog transmitters (e.g.,transmitters 418 (FIG. 4), 518 (FIG. 5)), however, can be set atparticular frequencies. Accordingly, transmission frequencies are chosenfor analog carrier signals 606 such that carriers 606 are spread wideacross wavelength spectrum 604 before consideration of other signals ofdifferent types.

Once process 600 verifies that the power level of analog signals 606 isoptimized, their noise level deemed acceptable, and that the severaloptical carriers are properly spaced apart without interference from oneanother, process 600 places the next signal in the successive wavelengthplacement scheme. Optionally, before placing additional signals, process600 may first calculate noise (not shown) across wavelength spectrum 604based on the placement of the optical carriers of analog carrier signals606, in order to more optimally place additional carriers in appropriateavailable wavelengths within wavelength spectrum 604.

FIG. 6B illustrates a graphical representation of successive wavelengthplacement of heterogeneous optical signals according to process 600following the initial wavelength placement illustrated in FIG. 6A.

In the exemplary embodiment, robust optical carriers are next chosen forplacement within portions along wavelength spectrum 604 that experiencethe worst noise conditions, that is, relatively near to or adjacent theplacement of analog carrier signals 606. In the example of FIG. 6B,first NRZ optical carriers 608(1), . . . 608(N′) are chosen for thissecond level of placement because they represent direct modulated/directdetection optical link carriers which can be adjusted in power so thatthe NRZ transmissions operate at an optimum target performance withinpredetermined appropriate margins.

NRZ optical carriers 608 are suited to fill the spectrum adjacent analogcarriers due to the “forgiving” nature of an NRZ signal. That is, firstNRZ optical carriers 608 are considered to have among the lowest SNR andthe highest noise tolerance of the heterogeneous signals, and areadditionally quite tolerant of the non-linear components generated byadjacent signals (i.e., analog carriers 606) along wavelength spectrum604. In an exemplary embodiment, first NRZ optical carriers 608 areplaced to effectively border the portion of wavelength spectrum aroundeach analog carrier signal 606. Alternatively, QPSK signals havecomparable carrier characteristics, and may be placed adjacent analogcarrier signals 606 in place of first NRZ optical carriers 608. A pocket609 is thereby formed between adjacent first NRZ optical carriers 608,which represents an area of relatively low noise within wavelengthspectrum 604.

After placement of robust first NRZ optical carriers 608, process 600may optionally recalculate noise across wavelength spectrum 604 to bothaccount for the addition of the new optical carriers (i.e., first NRZoptical carriers 608), and to more optimally identify pocket 609 forplacement of signals within wavelength spectrum 604 that have higher SNRrequirements.

FIG. 6C illustrates a graphical representation of further successivewavelength placement of heterogeneous optical signals according toprocess 600, following the wavelength placement illustrated in FIG. 6B.In the exemplary embodiment, optical signals having higher OSNRrequirements are next chosen for placement within pocket 609 (andsimilar regions of relatively low noise), and spaced from the placementof analog carrier signals 606. In the example of FIG. 6C, PAM4 opticalcarriers 610(1), . . . 610(N″), 16QAM optical carriers 612(1), . . .612(N′″), and 64QAM optical carriers 614(1), . . . 614(N″″) are chosenfor this third level of placement because they represent relatively highSNR optical link carriers which generally are tunable, but requirepremium areas of low noise within wavelength spectrum 604. In theexemplary embodiment illustrated, 16QAM optical carriers 612 may requirea lower SNR than 64QAM optical carriers 614, for example, but will stillrequire a significantly higher SNR than first NRZ optical carriers 608.According to the exemplary embodiment, 16QAM optical carriers 612 and64QAM optical carriers 614 may represent either coherent or digitalcarriers.

After placement of the higher SNR optical carriers 610, 612, and 614,process 600 may again optionally recalculate noise across wavelengthspectrum 604, as well as the non-linear effects across the differentcarriers, to account for the addition of the newly placed opticalcarriers. According to this optional embodiment, the power level on someof the optical carriers may be further adjusted in the event that theparticular SNR requirements for the intended modulation format of aspecific carrier is not satisfied. After such power adjustment,non-linear distortion and noise impact may then be recalculated.

FIG. 6D illustrates a graphical representation of a final successivewavelength placement of heterogeneous optical signals according toprocess 600, following the wavelength placement illustrated in FIG. 6C.In the exemplary embodiment, the remaining more robust, but generallylower power level, carriers are inserted into the remaining availableportions of wavelength spectrum 604. In the example of FIG. 6D, QPSKoptical carriers 616(1), . . . 616(N″″′) and second NRZ optical carriers618(1), . . . 618(N″″″) are chosen for this fourth level of placementbecause they represent generally tunable and tolerant carriers havinglower SNR requirements then the less tolerant carrier signals added asillustrated in FIG. 6C.

As described above, NRZ and QPSK carrier signals have some comparablecharacteristics with respect to robustness and SNR requirements, and maybe substituted for each other (or mixed) in the second and fourthplacement levels described herein, depending on particular signalcharacteristics such as symbol rate, baud rate, etc. Process 600 with usis configured to optimally choose the robust optical signals to add intowavelength regions having suboptimal noise levels, and according tomeasured and/or monitored signal and fiber characteristics. Once all ofthe optical carrier signals are so placed, non-linear effects and noiseimpact may be optionally recalculated.

FIG. 7 illustrates an alternative graphical representation of a threedimensional wavelength placement 700, as compared with the final carrierplacement of process 600, depicted in FIG. 6D. In this exemplaryembodiment, wavelength placement 700 is represented by wavelengthspectrum 702 (x-axis), efficiency 704 (y-axis), and power 706 (z-axis),illustrating wavelength allocation with a fiber strand (not shown)following placement according to a performance optimization process oralgorithm, for example, process 600 (FIG. 6).

As described above, when a single carrier is the only signal occupying afiber strand, interactions with other carriers are not a concern. Suchsingle carrier fiber strands are limited chiefly by the amount of powerthat particular fiber can handle without exerting distortion ontoitself. A signal with lower SNR requirement will generally be morerobust than one with a higher SNR requirement, and when two or more suchsignals are present within the same fiber, interaction and interferencebetween the signals must be addressed.

In the exemplary embodiment, wavelength placement 700 is illustrated asa three dimensional consideration of various requirements regardingpower, SNR, efficiency, adjacent noise characteristics, and bandwidthoccupancy. In an alternative embodiment, different signal and/or fibercharacteristics, including, without limitation: modulation format;polarization multiplexing; channel coding/decoding, including forwarderror correction; fiber length; aggregate carrier power; number ofoptical carriers; wavelength spacing among carriers; carrierconfigurability; carrier tenability; fiber type; amplification and/orloss devices; wavelength filters or splitters; and fiber distributionnetwork topology. In an alternative embodiment, placement 700 may beoptimized in consideration of a number of these additionalconsiderations, thereby rendering placement 700 as a five or sixdimensional allocation placement, or greater.

FIG. 8 is a flow chart diagram of an exemplary optical signal wavelengthallocation process 800 that can be implemented with fiber communicationsystems 300, 400, 500, and complimentary to process 600, depicted inFIGS. 3-6, respectively, and described above. Process 800 represents oneor more subroutines and/or algorithms for optical signal wavelengthallocation and configuration optimization. In an exemplary embodiment,process 800 begins at step 802. In step 802 process 800 performs a fibersegment analysis subprocess, explained further below with respect toFIG. 9. After completing the fiber segment analysis, process 800proceeds to step 804. In step 804, process 800 performs a signalanalysis subprocess, explained further below with respect to FIGS.10A-C. After completing the signal analysis, process 800 proceeds tostep 806. In step 806, process 800 performs a spectrum assignmentsubprocess, explained further below with respect to FIG. 11. In anexemplary embodiment, the subprocess of step 806 may include, or becomplementary with, process 600, depicted in FIGS. 6A-6D. Uponcompletion of spectrum assignment of optical carriers, process 800proceeds to step 808. In an exemplary embodiment, step 808 ends process800. In an alternative embodiment, step 808 represents a return to step802, in order to repeat process 800 one or more times as desired.

FIG. 9 is a flow chart diagram of an exemplary fiber segment analysissubprocess 900 that can be implemented with allocation process 800depicted in FIG. 8. In an exemplary embodiment, subprocess 900 embodiesstep 802, FIG. 8, or may begin from a prompt or call from step 802.Subprocess 900 proceeds from start to step 902. In step 902, subprocess900 determines the type of fiber (e.g., long fiber 310, FIG. 3) utilizedto broadcast the heterogeneous signals. In an exemplary embodiment, thefiber type is SM-SMF28. Subprocess 900 then proceeds to step 904, wherethe length of the fiber is determined. In an exemplary embodiment, thelength is determined in kilometers. Subprocess 900 then proceeds to step906, where latitude and longitude information regarding the fiber aredetermined. In an exemplary embodiment, such information considers bothinput and output from the fiber segment, as well as information thatprecedes and follows the fiber segment.

In addition to the general fiber information, subprocess 900 analyzesfiber parameters in consideration of the spectral placement ofheterogeneous signals. For example, at step 908, subprocess 900determines the presence of at least one of dispersion, loss, andnon-linear model parameters for SPM, CPM, and FWM. In an exemplaryembodiment, other parameters may be considered, as discussed above withrespect to FIGS. 6-7. Subprocess 900 then determines whether the fiberincludes an amplifier or lost device at step 910. In an exemplaryembodiment, step 910 is a decision step. If an amplifier or lost device(e.g., EDFA/AMP) is included, step 910 proceeds to step 912, where thenoise is recorded from the amplifier/loss device. In an exemplaryembodiment, step 912 further records power range and/or a non-linearparametric description of the amplifier/loss device. Once recorded,subprocess 900 proceeds from step 912 and returns to process 800 (FIG.8), and to step 804 specifically. If no amplifier/loss devices includedat step 910, subprocess 900 proceeds directly from step 910 to step 804.

FIGS. 10A-C illustrate a flow chart diagram of an exemplary signalanalysis subprocess 1000 that can be implemented with allocation process800 depicted in FIG. 8. In an exemplary embodiment, subprocess 1000embodies step 804, FIG. 8, or may begin from a prompt or call from step804. In an alternative embodiment, subprocess 1000 may proceed directlyafter steps 910/912, FIG. 9, or simultaneously with subprocess 900.

Subprocess 1000 proceeds from start to step 1002. Step 1002 is a returnpoint from the several subroutines included within subprocess 1000,described further below. Step 1002 returns subprocess 1000 to step 1004.Step 1004 is a decision step. In step 1004, subprocess 1000 analyzes theheterogeneous signals to determine whether there are any unassignedoptical signals within the heterogeneous signal group. If step 1004determines that there is at least one unassigned optical signal,subprocess 1000 proceeds to step 1006. If step 1000 for determining thatthere are no further optical signals to assign along the spectrum,subprocess 1000 instead proceeds to step 1007 which builds the opticalcarrier list along with the characterizing parameters, and thus a returnto subprocess 800 (FIG. 8), and specifically to step 806.

Step 1006 is also a decision step. In step 1006, subprocess 1000determines whether the optical signal at issue is an analog signal. Ifstep 1006 determines that the optical signal is an analog signal,subprocess 1000 proceeds to step 1008, where the optical signal isassigned an analog signal ID. If, however, the optical signal is notdetermined to be an analog signal, subprocess 1000 proceeds to step1010. After an analog signal ID is assigned in step 1008, subprocess1000 proceeds to an analysis subroutine 1012. Analysis subroutine 1012begins at step 1014. Step 1014 is a decision step. In step 1014,analysis subroutine 1012 determines whether the wavelength of theassigned optical signal is fixed. If the wavelength is determined to befixed, analysis subroutine 1012 records the fixed wavelength at step1016 and proceeds to step 1018. If though, step 1014 determines that thewavelength is not fixed, subroutine 1012 records the granularity and therange of the signal in step 1020, and proceeds to step 1018.

Step 1018 is a decision step. In step 1018, analysis subroutine 1012determines whether external modulation is being utilized. If suchmodulation is determined to be utilized, analysis subroutine 1012records the external modulation, as well as laser diode parameters, ifany, at step 1022 and proceeds to step 1024. If though, step 1018determines that external modulation is not being utilized, subroutine1012 records the laser diode parameters in step 1026, and proceeds tostep 1024. Step 1024 is a decision step. In step 1024, analysissubroutine 1012 determines whether power at an input is fixed. If thepower is determined to be fixed, analysis subroutine 1012 records theinput power at step 1028, and proceeds to step 1030. If though, step1024 determines that the input power is not fixed, the power range atthe input is recorded at step 1032, and analysis subroutine 1012 thenproceeds to step 1030.

Step 1030 is a decision step. In step 1030, analysis subroutine 1012determines whether there is amplification being implemented in the fibersegment. If such amplification is determined to be implemented, analysissubroutine 1012 records the location, amplifier characteristics, andoutput signal power at step 1034 and proceeds to step 1036. If though,step 1030 determines that there is no amplification implemented in thefiber segment, subroutine 1012 proceeds directly to step 1036. Step 1036is a decision step. In step 1036, analysis subroutine 1012 determineswhether there is a discrete loss in the fiber segment. If a discreteloss is detected, analysis subroutine 1012 records the location,characteristics, and output power loss at step 1038, and proceeds tostep 1040. If though, step 1036 detects no discrete loss in the fibersegment, analysis subroutine 1012 then proceeds directly to step 1040.

Step 1040 exits analysis subroutine 1012. Once analysis subroutine 1012is completed, the modulation bandwidth and modulation format of theassigned analog signal are determined at step 1042. At step 1044, thenoise level is determined, as well as the maximum and minimum signallevels. At step 1046, subprocess 1000 determines the electrical SNRrequirements for the assigned analog signal. At step 1048, subprocess1000 calculates the optical SNR requirements for the assigned analogsignal, and then proceeds back to step 1002.

Referring back to step 1010, if subprocess 1000 does not detect ananalog signal in step 1006, subprocess 1000 then determines whether theoptical signal at issue is one of a digital direct detection opticalsignal and a differential detection optical signal. That is, step 1010is a decision step. If step 1010 determines that the optical signal is adirect or differential signal, subprocess 1000 proceeds to step 1050,where the optical signal is assigned a direct detection signal ID. If,however, the optical signal is not determined to be adirect/differential signal, subprocess 1000 proceeds to step 1052. Aftera direct detection signal ID is assigned in step 1050, subprocess 1000proceeds to an analysis subroutine 1054. Analysis subroutine 1054 issubstantially identical to analysis subroutine 1012, except the samesteps are performed for the direct/differential signal, as opposed to ananalog signal.

Once analysis subroutine 1054 is completed, the modulation bandwidth andmodulation format, as well as the symbol rate, of the assigneddirect/differential signal are determined at step 1056. In step 1058,the noise level is determined, as well as the maximum and minimum signallevels. At step 1060, subprocess 1000 calculates the optical SNRrequirements for the assigned direct/differential signal, and thenproceeds back to step 1002.

Referring back to step 1052, if subprocess 1000 does not detect adirect/differential signal in step 1010, subprocess 1000 then determineswhether the optical signal at issue is a digital coherent opticalsignal. That is, step 1052 is a decision step. If step 1052 determinesthat the optical signal is a coherent signal, subprocess 1000 proceedsto step 1062, where the optical signal is assigned a coherent signal ID.If, however, the optical signal is not determined to be a coherentsignal, subprocess 1000 returns to step 1002. After a coherent signal IDis assigned in step 1062, subprocess 1000 proceeds to an analysissubroutine 1064. Analysis subroutine 1064 is substantially identical toanalysis subroutines 1012 and 1054, except the same steps are performedfor the coherent signal, as opposed to an analog or direct/differentialsignal.

Once analysis subroutine 1064 is completed, the modulation bandwidth andmodulation format, as well as the symbol rate, of the assigneddirect/differential signal are determined at step 1066. In step 1068,the noise level is determined, as well as the maximum and minimum signallevels. At step 1070, subprocess 1000 calculates the optical SNRrequirements for the assigned coherent signal, and then proceeds back tostep 1002. The steps outlined above, particular steps need not beperformed in the exact order they are presented, unless the descriptionthereof specifically require such order.

FIG. 11 is a flow chart diagram of an exemplary spectrum assignmentsubprocess 1100 that can be implemented with allocation process 800depicted in FIG. 8. In an exemplary embodiment, subprocess 1100 embodiesstep 6, FIG. 8, or may begin from a prompt or call from step 806. In analternative embodiment, subprocess 1000 may proceed directly after step1007, FIG. 10A, or simultaneously with subprocesses 900 and 1000.

Subprocess 1100 proceeds from start to step 1102. Step 1102 analyzes theheterogeneous signal to identify the noise level each individual signalgenerates onto itself different power levels as a standalonetransmission. In step 1102, subprocess 1100 further determines themargin from SNR requirements for the lowest power level of operation. Instep 1104, subprocess 1100 identifies the number of optical signals asan aggregate, and by type of optical signal. In step 1106, subprocess1100 determines the approximate wavelength and granularity for eachassigned signal. In step 1108, subprocess 1100 places the fixedwavelength optical signals at lowest acceptable power levels in aprimary position (e.g., FIG. 6A), and then determines the noise levelsurrounding neighboring wavelengths. Once the fixed wavelength opticalsignals are placed, subprocess 1100 optionally updates the noise levelband map at step 1110.

Once the fixed wavelength optical signals are assigned, subprocess 1100then proceeds to step 1112, where optical signals are placed atrelatively lower acceptable power levels, but which require relativelybetter channel conditions, and which also will realize the greatestimpact on fiber resources (e.g., FIG. 6B), that is, apart from the fixedwavelength optical signals. In an exemplary embodiment, after the firsttwo optical signal placements are made, subprocess 1100 proceeds to step1114, where a subroutine 1116 is called to verify and/or adjust theOSNR.

Subroutine 1116 begins at step 1118. In step 1118, subroutine 1116calculates the noise levels introduced by the one or more opticalsignals at issue. In step 1120, subroutine 1116 determines non-linear,self-induced noise. In step 1122, subroutine 1116 determines non-linearnoise which may have been induced from other carriers. In step 1124,subroutine 1116 determines amplifier non-linear noise from all carriers.In step 1126, subroutine 1116 determines attenuator non-linear noisefrom all carriers. The preceding steps of subroutine 1116 may beperformed in the order listed, in a different order, or simultaneously.Once the noise in nonlinear components are determined, subroutine 1116proceeds to step 1128. Step 1128 is a decision step. In step 1128,subroutine 1116 determines whether the verified OSNR levels shouldwarrant an adjustment in power levels. If the power level adjustment iswarranted, subroutine 1116 returns to step 1118 and recalculates thenoise levels and determines nonlinear components as described above. Ifno power level adjustment is warranted, on the other hand, subroutine1116 completes, and returns to the step following the call to subroutine1116 (in this case, step 1130). In an alternative embodiment, subroutine1116 may be called at any point after placement of a particular opticalsignal.

In step 1130, a third placement of optical signals is performed (e.g.,FIG. 6C) to assign the spectrum for those signals that are consideredgenerally robust, and thus assign such signals in relatively closeproximity to those signals that impact fiber resources mostsignificantly. Once so assigned, subprocess 1100 proceeds to step 1132,which calls subroutine 1116. Once subroutine 1116 is completed,subprocess 1100 proceeds from step 1132 to step 1134. In step 1134, afourth placement of optical signals is performed (e.g., FIG. 6D) toassign the spectrum for those signals that require the next best channelconditions, relative to the previously assigned signals, in theremaining unoccupied channels that provide such optimum conditions. Inan exemplary embodiment of step 1134, placement of optical signals isperformed to avoid channel condition deterioration through clustering ofthis particular group of optical signals. Optionally, after step 1134,subprocess 1100 may perform an additional step 1136, in order to placeoptical signals that are considered a generally more robust relativelyclose proximity to those signals that impact fiber resources mostsignificantly. Once these optical signals are so placed, subprocess 1100proceeds to step 1138, where subroutine 1116 is again called, and afterwhich, subprocess 1100 returns to process 800 (FIG. 8), specificallystep 808.

FIG. 12 illustrates an alternative hybrid ODC 1200 that can beimplemented with fiber communication systems 300, 400, and 500, depictedin FIGS. 3, 4, and 5, respectively. In an exemplary embodiment, hybridODC 1200 includes an optical portion 1202 and an HFC portion 1204.Optical portion 1202 includes an architecture similar to ODC 404 (FIG.4) and ODC 504 (FIG. 5), as described above. HFC portion 1204 includesan architecture similar to deep nodes 306 (FIG. 3), also describedabove. As illustrated, hybrid ODC 1200 includes at least one HFC portion1204 within its integrated structure, but may include a plurality of HFCportions 1204 within the device structure, that is, portions 1202 and1204 are not separated by a material distance.

In the exemplary embodiment, hybrid ODC 1200 connects to an optical hub(e.g., optical hub 302, 402, or 502) by downstream long fiber 1206 andoptional upstream long fiber 1208. Hybrid ODC 1200 communicates withoptical transceivers 1210 of respective end users (e.g., end users 308,406, 506) through short fibers 1212. Similarly, hybrid ODC 1200communicates with an optical transceiver 1214 of HFC portion 1204through dedicated fibers 1216. Whereas short fibers 1212 may spandistances of up to several thousand feet, dedicated fibers 1216 may spana distance of less than a few feet to connect optical portion 1202 toHFC portion 1204 within an integrated device architecture. According tothis alternative structure, hybrid ODC 1200 includes at least one inputoptical interface 1218 for communication with the optical hub (not shownin FIG. 12), and one or more output electrical interfaces 1220 forcommunication with respective end users (not shown in FIG. 12) that arenot configured to directly receive and transmit optical signals. Forsimplicity of illustration, output optical interfaces to transceivers1210 are not shown. In some embodiments, transceivers 1210, 1214 mayinclude separate transmitters and receivers.

As illustrated in the exemplary embodiments depicted herein, a pluralityof differing optical signals (i.e., analog, direct, differential,coherent, etc.) may be intelligently monitored and assigned to besimultaneously over the same fiber segment, and without requiring anyretrenching of new fiber to transmit the differing, heterogeneouscarriers. For network environments having limited fiber resources,implementation of the present systems and methods significantlyincreases the ability (e.g., of an optical hub) to multiplex opticalsignals efficiently. Such fiber-optic distribution networksadvantageously realize the ability to utilize different coexistingoptical transport systems within the same network. Such differentoptical transport systems, even though coexisting based on a set ofconfiguration parameters, may nevertheless be selected through one ormore of the several processes, subprocesses, and algorithms describedherein that optimize signal placement based on the different performancemetrics.

Intelligent Edge to Edge Optical System and Wavelength ServicesProvisioning

Further to the embodiments described above, it is desirable to providesystems and methods that are particularly capable of provisioningedge-to-edge wavelength connectivity services based on the performancecriteria described herein. It is further desirable to be able to operatethe network and its components such that the technological performancecan be optimized, both in general and in real-time, to factor in costcriteria in an efficient manner. The present embodiments provide such aprovisioning system for optical coherent transmissions, which has theadvantage of being capable of deployment with respect to non-coherenttransmission services, and particularly regarding transmissions thattraverse, and require management of resources, traversing and managingresources in the access-, regional-, and/or metro-/backbone-portions ofan optical edge-to-edge network.

As described above, the demand for transmission capacity for businessservices has been increasing exponentially. At the same time, broadbandaccess providers have been deploying fiber infrastructure deeper anddeeper, to the point of being in reasonably near proximity to virtuallyall customers. Within the sphere of cable operators, sizable portions ofoperator networks are migrating to N+0 architectures. In such migratedsystems, the physical distance to two a given consumer location isexpected to be approximately 1000 feet or less. Thus, is becoming costadvantageous to provide wavelength services through direct fiberconnectivity to customers.

However, despite this increasing extensive fiber coverage, the number ofavailable or unused fibers is still very limited. WDM techniques havebeen conventionally utilized to address this fiber scarcity problem.These conventional techniques provide some ability to manage thewavelength spectrum to assess optical resources, the optical signalpower, and the crosstalk noise optical carriers generate across thewavelength spectrum within a fiber.

Additionally, in the access network, optical links are known to utilizeanalog optics. An analog optic link implements intensity modulation ofthe optical carrier by the cable in the downstream direction, and RFspectrum in the upstream direction. Analog optic links are also referredto as subcarrier multiplexed optical links, because the different RFvideo and data channels are frequency-multiplexed to form the cable RFspectrum. Seen from an optical carrier perspective, the RF channels ofthis spectrum are considered to be subcarriers. In aggregate, thesesubcarriers form the RF signal that modulates the optical carrier.

DOCSIS transmissions, for example, require a high RF signal quality,that is, a high SNR. To achieve such high RF signal quality needs (alsorequired with other types of signals), the level of optical power usedwill also be very high, approaching the level where the operatingcondition of the fiber becomes non-linear. In such instances, there is alimit in the aggregate optical power that a single fiber can handle.Accordingly, the maximum number of optical carriers for a fiber isdetermined such that the aggregate optical power of the fiber can bemaintained within a tolerable threshold. Analog optical links, forexample, are deemed to operate at “high” optical power (e.g., as much as10 dBm or higher), non-coherent optical links such as intensitymodulated direct detect links (IM-DD), are deemed to operate at “medium”optical power, and coherent optical links are deemed to operate at “low”optical power (i.e., the lowest power level compared to the othertechnologies) due to the high sensitivity levels at which the coherentoptical links operate.

The embodiments described above present particular solutions that allowsuitable coexistence among all the different carrier types (i.e., inaddition to coexistence of different carrier signals of the same type)that share the same fiber. According to these embodiments, multiplecarrier types (e.g., analog, NRZ, PAM, QAM, QPSK, etc.) may beefficiently transmitted along a single fiber, whereas conventionalsystems transmit only multiple signals of the same carrier type. Thepresent systems and methods are configured to manage the optical energyemission from other optical channels and types. These advantageoustechniques improve over conventional attempts to address fiber scarcityin edge-to-edge optical networks, which string more fiber between theedge-to-edge end points, which is very expensive.

The systems and methods described further herein thus provide anadditional wavelength-based solution that utilizes wavelength resourceswithin the O-, S-, C-, and L-Bands.

FIGS. 13A-B illustrate a point-to-point optical connection 1300 betweentwo end points, EP 1 and EP 2, and a multi-end point network 1302 offive end points, EP-1 through EP-5. In an exemplary embodiment,wavelength services may be provided, for example, in the form ofpoint-to-point connectivity, such as optical connection 1300, or afully-meshed connected set of end points, as illustrated with respect tomulti-end point network 1302. For simplicity of explanation, multi-endpoint network 1302 is illustrated to include five end points; inpractice, a fully-meshed network may contain significantly more endpoints. The point-to-point solution of optical connection 1300 thus theforms the basic building block for multi-end point network 1302, whichincludes multiple point-to-point links 1304.

In an embodiment, each point-to-point link 1304 of multi-end pointnetwork 1302 may be indexed according to the suffixes (j, k) of therespective end points of the respective link 1304. Table 1, below,illustrates an association of end point indexes (n(j), n(k)), for pairsof opposing end points, to a respective optical connection index m(i),for multi-end point network 1302.

TABLE 1 n(j) n(k) m(i) 1 2 1 1 3 2 1 4 3 1 5 4 2 3 5 2 4 6 2 5 7 3 4 8 35 9 4 5 10

The association of end point indexes illustrated in Table 1 is thereforeof particular use to describe an edge-to-edge network. In edge-to-edgenetworks, point-to-point links 1304 might be completely confined to aparticular access network, or individual point-to-point links 1304 mightalso traverse the regional or metro networks associated with the accessnetwork. In some instances, one or more point-to-point links 1304 mightform a nationwide link traversing the backbone optical network. In manyinstances, a primary optical link carries the intended signal most ofthe time. The connection of the primary optical link might also have oneor more secondary links that are used for redundancy, such as in case oftransmission failures. Furthermore, the primary optical link may includea plurality of optical transport segments, and each such opticaltransport segment may have a different level of redundancy. Redundancyin the backbone portion of the network might be generally available,whereas redundancy in the access portion of the network might not beavailable, or only available at additional cost.

FIG. 14 is a schematic illustration of an exemplary architecture 1400for an end-to-end fiber infrastructure. In an exemplary embodiment,architecture 1400 includes a backbone portion 1402, a regional portion1404, and an access portion 1406. Backbone portion 1402 may, forexample, include a primary backbone network 1408 and a secondarybackbone network 1410, as well as a plurality of respective backbonewavelength switches 1412. Regional portion 1404 may, for example,include one or more regional networks 1414, as well as a plurality ofrespective regional wavelength switches 1416. Access portion 1406 may,for example, include one or more access networks 1418. In the exemplaryembodiment, customer premises equipment 1420 connects to an accessnetwork 1418 through a customer network 1422, which may include one ormore optical terminals 1424. In some embodiments, architecture 1400includes a primary path 1426, and a secondary path 1428.

In the cable environment, access portion 1406 of architecture 1400serves as the optical transport network between the hub or headend (seeFIG. 15, not shown in FIG. 14) and the subscriber (e.g., customerpremises equipment 1420) at the edge, or end-point, of the optical link.The hub/headend thus becomes the network location where the opticalsignals transition from access network 1418 to regional or metronetworks 1414. Conventional access cable environments have been runningfiber from the hub to an HFC fiber node (see FIG. 15, not shown in FIG.14). According to the present embodiments though, fiber runs may beadvantageously extended beyond the particular fiber node, such as to abusiness subscriber, a base station, or a residential subscriber.Connectivity between hub and node is described further below withrespect to FIG. 15.

FIG. 15 is a schematic illustration of an exemplary hub and fiber accessdistribution network 1500. In the example illustrated in FIG. 15,network 1500 includes an optical hub 1502 connected to a plurality ofoptical fiber nodes 1504 over optical fibers 1506. In the exemplaryembodiment, there is at least one fiber node 1504 for each fiber nodeserving area 1508. Fiber communication system 300 (FIG. 3), for example,may represent a detailed schematic embodiment of a particular fiber nodeserving area 1508. As further illustrated in FIG. 15, a particular oneof optical fiber nodes 1504 (i.e., test fiber node 1504 _(T) in FIG. 15)is connected to optical hub 1502 by both a primary fiber path 1510 and asecondary fiber path 1512.

In the exemplary embodiment, fiber node serving area 1508 represents alegacy HFC network that has been upgraded to a fiber deep architecture,as described above in greater detail with respect to FIG. 3, includingat least one ODC 304 for each serving area 1508 (depicted in greaterdetail, for example, as ODC 404, FIG. 4). In the example illustrated inFIG. 3, it can be seen that particular fiber segments, from the legacyHFC fiber nodes (e.g., fiber deep nodes 306) to hub 302, re-use existinglegacy fiber infrastructure. Fiber segments 312, from ODC 304 toend-points (i.e., end users 308) at the edge of the optical network,thus continue to be installed as traffic consumption increases, therebyadding a significant number of fiber strands to traverse the newportions (e.g., the last mile) of the optical network. As these newfiber segments 312 appear, individual end users/subscribers at the edgeof the network are provided with respective dedicated fibers, and ODC304 is optimally disposed at the subscriber location closest to wherewavelength and fiber management occurs (i.e., wavelength routing andfiber switching). In the case where fiber segments 312 have already beeninstalled in this last portion of the network (e.g., RFoG and EPONdeployments), and where there may be limited fiber resources availableto an increasing density of subscribers, additional wavelengthmultiplexing can be implemented.

In some embodiments, the selection of a wavelength, for dedication to aparticular fiber that connects a particular end user 308, may beachieved by manually connecting the appropriate wavelengthde-multiplexer output to the appropriate fiber strand (e.g., downstreamshort fiber 412) that transmits to the given end user/subscriber308/406. In an alternative embodiment, such functionality may beperformed automatically, for example, by implementation of acontrollable non-blocking optical switch (e.g., optical switch 448, FIG.4), such that a desired de-multiplexing port can, on command, be matchedto the desired subscriber fiber (e.g., short fiber 412).

FIGS. 16A-B illustrate sectional views of an exemplary fiber cable 1600and fiber conduit 1602, respectively. Fiber cable 1600 includes, forexample, a fiber sheath 1604 surrounding a one or more fiber tubes 1606,with each fiber tube 1606 including a plurality of fiber strands 1608.In some embodiments, fiber cable 1600 further includes a centralstrengthening member 1610 disposed along the length of fiber sheath1604. Optical fiber tubes 1606 are generally deployed in bundles withina cable carrying a plurality fibers, typically in multiples of 12 (e.g.,12 or 24 fiber strands 1608). These fibers are terminated withconnectors (not shown) that reside in a cabinet or a termination box(also not shown), or are spliced (e.g., fusion splicing) to continuingfibers that extend the length of a fiber segment. In some cases, a fewfibers are peeled off from the bundle to connect to a lower fiber countcable (not shown). In at least one embodiment, an external messengercable (not shown) is provided when utilized in aerial plants, where asheath (or multiple sheaths) of fiber may be stranded between utilitypoles from splicing point to splicing point.

In other examples, fiber cable 1600 is deployed in above-ground orunderground conduits, such as fiber conduit 1602, illustrated in FIG.16B. Fiber conduit 1602 includes, for example, a plurality of sheaths offiber cable 1600, FIG. 16A. In this example, individual fiber cables1600 within fiber conduit 1602 contain differing amounts of fiber tubes1606. According to the present systems and methods, the optical networkis configured to be capable of managing the numerous fibers deployedthroughout the optical network, as well as the respective wavelengthsdedicated thereto. That is, the present embodiments are advantageouslycapable of implementing techniques to identify each fiber sheath 1604within fiber conduit 1602, each fiber tube 1606 within the identifiedfiber sheaths 1604, and each fiber strand 1608 within the identifiedfiber tubes 1606.

In conventional practice, a color coding scheme is used to identifyfibers within a 12- or 24-bundle of fiber strands 1608 within a fibertube 1606. This conventional color coding scheme labels label each fiberwith a 1-to-12 or 1-to-24 number. A different color coding scheme isalso conventionally known to identify fiber tubes 1606 within fibersheath 1604. In the example fiber conduit 1602 illustrated in FIG. 16B,if it is assumed that 24 fiber strands 1608 for each fiber sheath 1604,fiber conduit 1602 will include three fiber sheaths 1604 having 144fiber strands 1608, and four fiber sheaths 1604 having 96 fiber strands.The present systems and methods may be advantageously configured toseparately identify individual fiber strands 1608, and/or identify fiberstrands 1608 according to these conventional color coding schemes. Oncefiber strands 1608 are identified, the present network is furtherconfigured to identify wavelength in channel parameters, as illustratedbelow with respect to FIG. 17.

FIG. 17 illustrates an exemplary channel map 1700 of a portion of theC-Band and L-band. In the exemplary embodiment, individual channels ofthe C-Band and L-Band are according to ITU-T G.694.1. Channel map 1700illustrates the identification of wavelength usage in each fibersegment, according to a determination of the availability of particularoptical transmission bands. Portions of the C-Band and L-Band areillustrated in FIG. 17 for purposes of explanation. The C-band, forexample, is considered a premium usage band because it can leverageamplification through EDFAs. In this example, the L-Band is shown to beavailable, but may only be desirable for use where amplification is notnecessary.

O-band optical carriers (e.g., 1310 nm, not shown in FIG. 17) may beused in the access portion of the network (e.g., access portion 1406,FIG. 14), but these carriers are not likely to be used to provideend-to-end services, since they are generally limited to legacyservices. Nevertheless, the present embodiments may furtheradvantageously consider the O-band carriers in the processes andsubprocesses described further below. The consideration of theseadditional carriers allows the present embodiments to more efficientlyfilter out the portion of the spectrum relating to these carriers, andto further accurately assess the impact that the optical power therefrom will have on other optical carriers (see FIGS. 6-7, above)utilizing the same fiber.

In managing the identified wavelengths and channels (e.g., FIG. 17) forthe identified fiber strands (e.g., fiber strands 1608, FIG. 16), thepresent embodiments further configured to advantageously a variety ofoptical switches, wavelength demultiplexers, multiplexers, and ROADMs.For example, as illustrated with respect to FIG. 4, ODC 404 is describedto utilize an optical switch or an N×N non-blocking optical switch.Additionally, or alternatively, ODC 404 may be configured to implementdemultiplexers having a single-fiber input and an output across aplurality of fibers on different wavelengths, and/or multiplexers thatinput many fibers on different wavelengths and a single-fiber output.

In at least some embodiments, the present embodiments utilize areconfigurable optical add-drop multiplexer (ROADM). Such ROADMimplementations may, for example, utilize only a single drop-port or asingle add-port for each demultiplexer or multiplexer therein, but mayalternatively utilize a plurality add- and/or drop-ports. In the casewhere a plurality add- and/or drop-ports are utilized, the respectiveadditional wavelengths (or colors) would be missing from the bypasssection of the ROADM. In an embodiment, the ROADM may be implementedwith a single layer, or include multiple layers having internal opticalfiber switches to manage the multiple-fibers-in and multiple-fibers-out.Such internal optical fiber switches may be, for example, implemented ona wavelength level. That is, a wavelength selective switch may be basedon MEMS, Liquid Crystal, or Liquid Crystal over Silicon structures.

FIG. 18 is a schematic illustration of an exemplary topology 1800 of acable-based end-to-end fiber infrastructure. In overall structure,topology 1800 is similar to architecture 1400, FIG. 14, above, andincludes a backbone portion 1802, a regional portion 1804, and an accessportion 1806. Backbone portion 1802 may include a primary backbone 1808and a secondary backbone 1810. In this example, primary backbone 1808 isillustrated to be a 12-fiber ring, and secondary backbone 1810 isillustrated to be a 6-fiber ring. Further to this example, regionalportion 1804 _(A) is illustrated to be a regional network 1812 _(A)(operator A) 96-fiber ring, where as regional portion 1804 _(B) isillustrated to be a regional network 1812 _(B) (operator B) 48-fiberring. Access portions 1806(2) and 1806(3) are each similar to thegeneral topology of access network 1500, FIG. 15 (finer details of HFCnode serving area not shown in FIG. 15).

In this exemplary embodiment of the present disclosure, an intelligentconfiguration capability establishes a signal connectivity betweenrespective two end points, and by leveraging such information as: (A)knowledge of the capabilities of the respective end devices; (B)knowledge and control of wavelength occupancy (e.g., FIG. 17) in thefiber strands (e.g., FIG. 16) available between two end points withinthe fiber network routes; and (C) through leveraging the control,configuration, and connectivity of individual optical transmissioncomponents, as described above, and further below. Accordingly, adetailed, cable-specific example of topology 1800 is illustrated for theedge-to-edge cable infrastructure of FIG. 18.

In an exemplary embodiment of topology 1800, a wavelength is provisionedfrom a subscriber (e.g., end user 308, FIG. 3) in node serving area 1814_(A) (i.e., shaded area, in this example), within the Hub '2 of accessportion 1806 _(A), and sent to an end user in node serving area 1814_(B) (separately shaded) within Hub 3. Accordingly, the primary path ofthe provisioned wavelength traverses Hub'2, Hub '3, Hub '4, and Hub '0from regional network 1814 _(A) of operator A, connects to Hub 0 throughprimary backbone 1808 and then traverses 1, Hub 2, and Hub 3 in regionalnetwork 1814 _(B) of operator B before reaching the node where the endsubscriber is located. The secondary wavelength path traverses Hub '2and Hub '1 from regional network 1814 _(B) of operator A, connects toHub 4 through secondary backbone 1810, and then traverses Hub 3 inregional network 1814 _(B) of operator B, before reaching the nodewithin Hub 3 where the end subscriber is located.

FIG. 19 is a block diagram of an exemplary sequence 1900 of componentstraversed by optical signals of selected or desired wavelengths.Sequence 1900 may include, for example, one or more of a origintransceiver 1902, a first origin access fiber segment 1904 (e.g., forthe first/last mile), an origin node multiplexer 1906, a second originaccess fiber segment 1908, an origin hub ROADM 1910, an origin corefiber segment 1912, an origin optical amplifier 1914, a core ROADM 1916,a destination optical amplifier 1918, a destination core fiber segment1920, a destination ROADM 1922, a first destination access fiber segment1924, a destination node demultiplexer 1926, a second destination accessfiber segment 1928 (e.g., for the last/first mile), and a destinationtransceiver 1930.

In exemplary operation of the sequence 1900, key parameters of thetransmitted optical signals are managed, according to the embodimentsdescribed above, so that the wavelengths of the optical signals ofdifferent carrier types may coexist sharing the common fibers. These keyparameters may include the transmit power, the modulation type (coherentor non-coherent), the modulation order, the modulation bandwidth orsymbol rate, and the wavelength or center frequency. In at least someembodiments, emission in adjacent channels and/or other channels is alsoa key parameter that are also managed to optimize the coexistence ofdifferent carrier types transmitted on the same fiber.

FIG. 20 is a graphical illustration depicting an exemplary powermanagement distribution 2000. Distribution 2000 emphasizes how a maximumpeak power 2002 can be managed for a particular transmit channel 2004.Distribution 2000 further illustrates how maximum allowable energy maybe defined outside of transmit channel 2004, for example, in adjacentchannels 2006 and other channels 2008 in the wavelength spectrum.Through this illustrative distribution 2000, the person of ordinaryskill in the art may more readily determine techniques to manage thepower and unwanted noise emissions across wavelength spectrum, tooptimize the use of fiber resources. In the exemplary embodiment, theseparameters may be further managed, according to the embodiments herein,to optimize transmission noise emission performance requirements forwavelength service subscribers, such that the subscribers may adhere toparticular service-level agreements (SLAs).

Distribution 2000 illustrates optimal management of restrictions basedonly upon the wavelength or center frequency of the channel, as well asits immediate environment. Nevertheless, the present embodiments arefurther capable of advantageously managing the optimal placement ofdifferent carrier types within the same fiber in consideration ofadditional restrictions, such as where the transmitted signaloriginates. The signal origin may be an important consideration factorbecause certain portions of the network, such as the backbone portion,would likely require different optimization considerations than otherportions of the network, since the backbone portion would typically beconsidered to have greater value than the access portion or theregional/metro portion of the network. Table 2, below, lists examples ofthe maximum launch power per channel at the access portion of thenetwork, versus the maximum launch power per channel at the metro andbackbone portions of the network. Thus, as shown in Table 2, the launchpower may experience different restrictions based on where the signaloriginates.

TABLE 2 Ch. Launch Power at Ch. Launch Power Access at Metro/Backbone 200 GHz +6 dBm  200 GHz +3 dBm  100 GHz +3 dBm  100 GHz 0 dBm   50 GHz0 dBm   50 GHz −3 dBm   25 GHz −3 dBm   25 GHz −6 dBm 12.5 GHz −6 dBm12.5 GHz −9 dBm

As can be seen from Table 2, optical power in the metro and backboneportions of the network are lower than the optical power in the accessportion of the network, so that a greater number of channels the isallowed, with fewer unwanted emissions, along the fiber wavelengthspectrum in the portions of the network where it is most the desirableto optimize for capacity. In at least some embodiments, in addition tothe individual optical signal parameters considered above, the presentembodiments are still further capable of factoring into the carriercoexistence determinations aggregate fiber parameters, such as themaximum aggregate optical power. That that is, present techniques mayfurther advantageously factor in the additive effect of all signalstransmitted within a particular fiber to prevent non-linear behavior ofthe fiber, which could impact the overall capacity in a fiber strand.

In order to optimize capacity in a shared fiber environment, the presentsystems and methods implement innovative and precise managementtechniques of the parameters of the different optical carrier types.From the perspective of subscribers that use their own opticaltransmitters, such subscriber transmitters would be required to adhereto a Carrier Coexistence Agreement (CSA) that operates in cooperationwith the principles described herein. In the case where the serviceprovider has control of the transmitters, the service provider wouldalso be required to obey the configuration thresholds of the same CSA,thereby allowing the service provider to enable SLAs when providingend-to-end wavelength services.

The innovative techniques of the present embodiments further enabledevelopment of optimal wavelength service provisioning strategies toidentify and more efficiently utilize wavelength resources, such that aservice provider, for example, is able to more accurately charge thesubscriber for services based on the implementation complexity,performance, and/or cost of the services. That is, through the noveltechnical solutions presented herein, less guesswork is required toestimate service costs per subscriber, per fiber node serving area, orper access network.

Although, in theory, there might be numerous options to use anywavelength in the C-Band and L-Band, in practice, there are particularconsiderations that must be factored into the availability and use oftransmitters and receivers at the different wavelengths of these bands.Additionally, other considerations, such as the need for amplification(e.g., by EDFAs), or that EDFAs are not available in the L-Band, mustalso be weighed. At present, conventional non-coherent transmitters andreceivers are less costly than coherent transmitters and receivers.However, because coherent signals can be efficiently packed in acomparatively very small bandwidth in relation to the non-coherentsignals, utilization of the coherent technology described hereinsignificantly improves the efficiency of utilizing existing fiberresources. Accordingly, the reduction in the need for retrenching,resulting from the increased efficiency achieved from coherenttechnology, will significantly outweigh the increased cost of theindividual coherent transmitters and receivers that are used toimplement the technology. These cost benefits are realized even if therelative cost of the coherent components does not decrease over timewith respect to their non-coherent counterparts (which is neverthelessanticipated).

These efficiency benefits are particularly advantageous two operators inthe cable environment, since the present cable operators typically havesignificant penetration of fiber, but only a limited number of fiberstrands available for further expansion. Therefore, althoughnon-coherent wavelength services may be initially considered to exhibitlower end point costs (e.g., from less expensive hardware components),operation of the non-coherent wavelength services to the end point willbe, in fact, more costly overall, due to the considerably greaterbandwidth and power resources consumed by the non-coherent technology.Several of the algorithms described further below specificallydemonstrate how, in many scenarios, it is more cost effective toimplement wavelength services using the coherent systems and methodsdescribed herein, as compared with conventional non-coherenttechnologies.

As described above, coherent optical links have greater sensitivity thannon-coherent optical links, and comparatively require only very lowtransmit power. As also described above, the maximum aggregate power ina fiber is a key parameter to evaluate, as a capacity-limitingphenomenon, due to the non-linear behavior that may result fromoverpowering the fiber. This sensitivity advantage experienced bycoherent links further enables transmissions over longer distanceswithout additional amplification, thereby further reducing the hardwarecosts using coherent technology.

As described above with respect to FIG. 17, channel map 1700 includesportions of the C-Band and the L-Band. As described further herein, acriteria and techniques of wavelength mapping and selection are providedto more efficiently allocate the channels of an available spectrum, suchas some or all of the channels illustrated in channel map 1700.Typically, the access network will be expected to have limited fiberstrands available from the Hub to the node. Nevertheless, it may beassumed that, because new fiber must be installed from the node to eachnew subscriber, sufficient fiber resources will be available for thislast node-to-subscriber segment.

It is further expected that limited fiber resources are available fromHub-to-Hub, as well as in the backbone portion of the network. That is,the backbone portion, which includes the longest distance links, haslimited fiber resources, and is the portion of the network that is morecarefully managed and is most likely to include amplification stages. Aprovider's regional networks may have greater fiber availability thanwould their backbone portion, but the provider might also have a varietyof optical technologies using those additional resources. Theutilization of all such resources influences the cost and performance toprovide wavelength services. Accordingly, the wavelength selectionstrategy of the present techniques is further advantageously configuredto consider the effect on the network and fiber wavelength distributionfrom these other resources.

For wavelength services that traverse shorter distances there may not bea need for amplification. In such instances, that is, for services thatmight traverse only the access portion or the access network and ashorter path through a few hubs, the wavelength selection strategy mightonly allocate the L-Band and a smaller portion of the C-Band. However,for longer distance transmissions, where multiple hubs or a portion ofthe backbone are traversed, the C-Band, which has amplificationcapabilities, might be more optimally allocated.

The present systems and methods are therefore configured to implement acomprehensive database to perform resource analysis and cost factoring.The comprehensive database encompasses information regarding theavailable fiber resources from end-to-end, as well as the wavelengthallocation per fiber segment. Accordingly, even if certain portions ofthe wavelength spectrum are unused, certain wavelengths may benevertheless reserved for services that are often used by operators.Such reserved wavelengths might represent those typically used in EPON,Gigabit Ethernet, analog optics, and other signals, for example. Thus,the comprehensive database may include a detailed wavelength channel map(e.g., channel map 1700, FIG. 17), as well as information for additionaloptical signal attributes including one or more of the type of signal,the modulation order, the bandwidth or symbol rate, the transmit powerat source, the peak optical power in fiber segment, in the centerfrequency or wavelength, etc.

A significant attribute of the fiber segment to consider is the costfactor per optical signal in that segment. Factors that contribute tothis cost factor include such considerations as the scarcity ofwavelengths and bandwidth in that segment, the center frequency, and theband associated with that center frequency. Additionally, L-Bandchannels are considered at present to be less expensive than C-Bandchannels, due to the lack of amplification in the L-Band. Anothersignificant cost factor to consider is the launch power. Since there isnon-linear behavior induced by high aggregate optical power within afiber strand, in at least one embodiment, the present techniques addressthis limitation by imposing a threshold above which a cost premium isadded to transmit near, at, or above this threshold value.

The present techniques further, in an embodiment, determine thatflexible wavelength end points exhibit lower operating costs, since theoperator is able to re-arrange the wavelengths to accommodate servicesfor other subscribers. Fixed wavelengths are thus more restrictive.Accordingly, if a subscriber is buying fixed wavelength services, theoperator may then analyze the available end-to-end wavelength optionsand provide the potential subscriber with a list of potentialwavelengths to use. Table 3 illustrates a list of fiber traversal costelements based on the length and the section of the network beingutilized. Table 3A illustrates the cost elements with respect toutilization of one's own network fiber, and Table 3B illustrates thecost elements with respect to utilization of a peered network fiber.

TABLE 3A (Own Fiber) Fiber Segment Cost Backbone fb(L) Regional fr(L)Access fa(L)

TABLE 3B (Peered Fiber) Fiber Segment Cost Backbone p * fb(L) Regionalp * fr(L) Access p * fa(L)

Table 4 illustrates a list of sample node traversal cost elements basedon the length and the section of the network being utilized. Table 4Aillustrates the per node cost in one's own network, and Table 4Billustrates the per node cost in the peered network. In someembodiments, the access node, which is the gateway to the region, isconsidered to be a regional network node from a cost perspective, eventhough the access node is effectively at the regional boundary.Similarly, a regional node functioning as the gateway to the backboneportion (i.e., at the backbone boundary) is considered to be a backbonenetwork node from a cost perspective.

TABLE 4A (Own Network) Node Cost Backbone Network Node nb RegionalNetwork Node (not nr in Backbone boundary) Access Network Node (not inna Regional boundary)

TABLE 4B (Peered Network) Node Cost Backbone Network Node p * nbRegional Network Node (not p * nr in Backbone boundary) Access NetworkNode (not in p * na Regional boundary)

Table 5 illustrates a list of sample bandwidth cost factors based on thelength and the section of the network being utilized. Table 5Aillustrates the bandwidth cost in one's own network, and Table 5Billustrates the bandwidth cost in the peered network. Althoughamplification may be included in the backbone portion of the network, ifamplification is desired in other portions of the network, such as theregional portion of the network, additional cost are added to thedeterminations illustrated below. In an exemplary embodiment, thepresent techniques implement a channel selective amplification systemutilizing ROADMs together with EDFAs. However, other hardwareconfigurations are contemplated, as described above.

TABLE 5A (Own Network) Segment Cost Factor Backbone Network g(bw)Regional Network Node g′(bw) Access Network Node g″(bw)

TABLE 5B (Peered Network) Segment Cost Factor Backbone Network g(bw)Regional Network Node g′(bw) Access Network Node g″(bw)

According to the present systems and methods, wavelength services areadvantageously performed utilizing fully automated wavelengthmultiplexing techniques, together with optical switching technology.Additionally, or alternatively, the present embodiments are implementedin nearer physical proximity to the network edge, where fewer changesare expected over time. In some embodiments, the present systems andmethods may further implement manual fiber connectivity and manualselection of specific wavelength de-multiplexers as an optionalcomplementary technique with portions of the embodiments disclosedherein. At the core or backbone portion of the network, frequent changesand fiber manipulations are expected, and therefore a fully automatedsystem is anticipated at such locations to maximize the efficiency ofthe present systems and methods. Some of manual operations at thebackbone/core are possible within the scope of the present application,but are generally considered less desirable.

An optimal methodology to provide wavelength services is described withrespect to the flow diagrams illustrated in FIGS. 21-23, below. Theexemplary processes and subprocesses described therein summarizeparticular criteria and cost assessments that are applied to thetechnology of the different portions of the network to provisionwavelength connectivity services and thereby maximize efficiency.

FIG. 21 is a flow chart diagram of an exemplary point-to-point networkprovisioning process 2100 that may be implemented with the embodimentsdescribed above. Provisioning process 2100 may be implemented by aprocessor of a wavelength-based point-to-point network provisioningsystem, disposed, for example, within an optical hub of the network.Alternatively, the network provisioning system may be located in, oroperate from, another portion of the optical communications network.Process 2100 begins at step 2102. In step 2102, process 2100 defines orselects all n(j) end points of the desired point-to-point network. For aquantity N of end points, there are a total of M connections, asrepresented by the following equation:

$\begin{matrix}{M = \begin{pmatrix}N \\2\end{pmatrix}} & \left( {{Eq}.\mspace{11mu} 1} \right)\end{matrix}$

Step 2104 is a decision step. In step 2104, process 2100 determines ifredundancy is required for all M connections. If redundancy is required,process 2100 proceeds to step 2106, and sets a redundancy value r=1. If,in step 2104, process 2100 determines that redundancy is not required,process 2100 proceeds instead to step 2108, where the redundancy valueis set to r=0. In step 2110, process 2100 determines, for all (n(j),n(k)) end point pairs, all m(i) connections (see e.g., Table 1, forN=5), and sets the value m=1.

In step 2112, process 2100 executes wavelength and fiber path selectionsubprocess 2200, described below with respect to FIG. 22. Aftercompletion of subprocess 2200, process 2100 proceeds to step 2114. Step2114 is a decision step. In step 2114, process 2100 determines if m=M.If, in step 2114, process 2100 determines that m=M, process 2100concludes, or optionally returns to subprocess 2200 to reevaluate thesystem. If, however, in step 2114, process 2100 determines that m≠M, thevalue m is incremented such that m′=m+1, and process 2100 then returnsto step 2112 and repeats subprocess 2200 (e.g., at least until m=M).

FIG. 22 is a flow chart diagram of an exemplary wavelength and fiberpath subprocess 2200 that may be implemented with provisioning process2100, FIG. 21. In the exemplary embodiment, wavelength and fiber pathsubprocess 2200 is implemented with respect to at least a single opticallink between two end points (see e.g., FIG. 13, above).

Subprocess 2200 begins at step 2202, in which subprocess 2200 indexes,or retrieves an index (e.g., Table 1, above) of, the (n(j), n(k)) pairsof end points and the corresponding m(i) connections/associations. Instep 2204, subprocess 2200 implements algorithms, e.g., mesh topologypath discovery algorithms, to determine a set of all potential fiberpaths between end points within the fiber topology (e.g., topology 1900,FIG. 19). In step 2206, subprocess 2200 determines a subset of availablefiber paths between end points based on the available wavelengths onevery fiber segment of each potential fiber path. In step 2208,subprocess 2200 determines which subset of fiber paths meet particularperformance requirements (e.g., bandwidth, latency, noise, etc.) usingthe bandwidth required by the point-to-point link.

In step 2210, subprocess 2200 determines, for each resulting fiber path,the set of all nodes crossed by the path, as well as a set of all suchpaths and their corresponding lengths. In step 2212, subprocess 2200adds fiber path selection criteria (e.g., maximum number of nodes,maximum length, etc.) and adjusts the rate of the calculation accordingto the added criteria, and/or filters the set of potential fiber pathsbased on the added criteria. Step 2214 is a decision step. In step 2214,subprocess 2200 determines if redundancy is required (i.e., r=1, fromstep 2106, FIG. 21) for the particular fiber connection link beingevaluated. If, in step 2214, subprocess 2200 determines that redundancyis required, subprocess 2200 proceeds to step 2216, and provides the setof fiber path pairs with a highest degree of orthogonality. In thisdisclosure, it is recognized that fully orthogonal paths will not sharea common segment in practice.

If, however, in step 2214, subprocess 2200 determines that redundancy isnot required, subprocess 2200 proceeds to step 2218, and provides theset of all fiber path pairs, and for the upstream and/or downstreamdirections. Step 2220 is a decision step. In step 2220, subprocess 2200determines if at least one fiber pair path includes at least onesecondary path (i.e., where r=1) meeting the path selection criteria. Ifat least one fiber pair path is found with a corresponding secondarypath, process 2200 then proceeds to step 2222, in which subprocess 2200executes a cost subprocess 2300, described below with respect to FIG.23. If, however, in step 2220, a corresponding secondary path meetingthe path selection criteria is not found, subprocess 2224 then proceedsto step 2224, in which the selection criteria are relaxed, in thedatabase is updated to record the relaxed criteria, and the set of fiberpaths is recalculated before proceeding on to step 2222, and executionof subprocess 2300 thereby.

In step 2226 process 2200 estimates the cost of each fiber path, basedon the results obtained from cost subprocess 2300, and according to thepath of selection criteria (e.g., original or relaxed) of the set. Theresults obtained from cost subprocess 2300 assesses, for example, thecost of each traversed node and each traversed segment, the impact ofthe wavelength center frequency and bandwidth, the total traversedlength, etc. In step 2228, subprocess 2200 selects the fiber path orfiber path pairs, and the associated wavelength, that meet(s) the fiberpath selection performance criteria at the lowest cost. Upon selectionof the fiber path(s) in step 2228, subprocess 2200 returns to step 2114in process 2100, FIG. 21.

FIG. 23 is a flow chart diagram of an exemplary cost subprocess 2400that may be implemented with provisioning process 2100, FIG. 21, andwavelength and fiber path subprocess 2200, FIG. 22. Cost subprocess 2300begins at step 2302, in which subprocess 2300 calculates the cost ofeach traversed node based on the node location, including the impact ofwhether the node is from one's own facility versus a peered facility(see e.g., Tables 4A-B). In step 2304, subprocess 2300 calculates thecost contribution of each fiber segment based on the location of theparticular fiber segment, its length at a particular wavelength (e.g.,C-Band vs. L-Band), and the impact of an own-versus-peered fiber (Ce.g., Tables 3A-B). In step 2306, subprocess 2300 calculates the costfactor as a function of bandwidth, considering the impact of own-versuspeered-facilities (see e.g., Tables 5A-B).

Step 2308 is an optional step. In step 2308, subprocess 2300 adjusts thecost calculations if channel selective amplification is needed ordesired. Step 2310 is also an optional step. In step 2310, subprocess2300 recalculates the preceding costs for a corresponding secondarypath, i.e., if redundancy was required for the particular path.

In step 2312, subprocess 2300 calculates and adds at least oneadditional cost factor based upon the required noise conditions of theselected channel. Step 2314 is also an optional step. In step 2314,subprocess 2300 calculates and adds a further cost factor to compensatefor peak power being greater than an allowed power level, if desired.

In step 2316, subprocess 2300 calculates a further cost adjustmentdepending on whether the transmission is a fixed-versus-configurablewavelength center frequency. In an exemplary embodiment, the furthercost adjustment adds a premium value for fixed wavelength transmissions.In step 2318, a still further cost adjustment is calculated depending onwhether a given end point is managed and/or owned by a service providerfor which the service costs are being assessed. Upon completion of step2318, subprocess 2300 completes, and returns to step 2226 of wavelengthand fiber path selection subprocess 2200, FIG. 22.

Exemplary embodiments of fiber communication systems and methods aredescribed above in detail. The systems and methods of this disclosurethough, are not limited to only the specific embodiments describedherein, but rather, the components and/or steps of their implementationmay be utilized independently and separately from other componentsand/or steps described herein. Additionally, the exemplary embodimentscan be implemented and utilized in connection with other access networksutilizing fiber and coaxial transmission at the end user stage.

Although specific features of various embodiments of the disclosure maybe shown in some drawings and not in others, this is for convenienceonly. In accordance with the principles of the disclosure, a particularfeature shown in a drawing may be referenced and/or claimed incombination with features of the other drawings. For example, thefollowing list of example claims represents only some of the potentialcombinations of elements possible from the systems and methods describedherein.

a(i). An optical network communication system, comprising: an opticalhub including an intelligent configuration unit configured to monitorand multiplex at least two different optical signals into a singlemultiplexed heterogeneous signal; an optical distribution centerconfigured to individually separate the at least two different opticalsignals from the multiplexed heterogeneous signal; at least one fibersegment connecting the optical hub and the optical distribution center,the at least one fiber segment configured to receive the multiplexedheterogeneous signal from the optical hub and distribute the multiplexedheterogeneous signal to the optical distribution center; and at leasttwo end users, each including a downstream receiver configured toreceive one of the respective separated optical signals from the opticaldistribution center.

b(i). The system of claim a(i), wherein the intelligent configurationunit comprises a processor and a memory, and an optical multiplexer.

c(i). The system of claim b(i), wherein the intelligent configurationunit further comprises an optical multiplexer.

d(i). The system of claim b(i), wherein the intelligent configurationunit further comprises at least one of a control interface and acommunication interface to receive from and send information to anoptical multiplexer.

e(i). The system of claim a(i), wherein the optical distribution centercomprises a node optical demultiplexer configured to demultiplex themultiplexed heterogeneous signal.

f(i). The system of claim a(i), wherein the optical hub comprises atleast two downstream transmitters, each configured to transmit one ofthe at least two different optical signals, respectively.

g(i). The system of claim f(i), wherein each of the at least two endusers further includes an upstream transmitter, wherein the opticaldistribution center further comprises a node optical multiplexer, andwherein the optical hub further comprises at least two upstreamreceivers configured to receive a different optical signal fromdifferent ones of the transmitters of the at least two end users,respectively.

h(i). The system of claim f(i), wherein the intelligent configurationunit is further configured to multiplex the at least two differentoptical signals from the at least two downstream transmitters.

i(i). The system of claim a(i), wherein the at least two differentoptical signals include two or more of an analog signal, an intensitymodulated direct detection signal, a differential modulated signal, anda coherent signal.

j(i). The system of claim a(i), wherein the at least two end userscomprise at least two of a customer device, customer premises, abusiness user, and an optical network unit.

k(i). The system of claim a(i), further configured to implement coherentdense wavelength division multiplexing with a passive optical networkarchitecture.

l(i). The system of claim k(i), wherein the at least two end usersinclude at least N subscribers, and wherein the system comprises atleast two fiber segments for each N subscribers.

m(i). The system of claim a(i), further configured to implementwavelength filtering and injection locking.

n(i). The system of claim m(i), wherein the at least two end usersinclude at least N subscribers, and wherein the system comprises atleast three fiber segments for each 2N subscribers.

a(ii). A method of distributing heterogeneous wavelength signals over afiber segment of an optical network, comprising the steps of: monitoringat least two different optical carriers from at least two differenttransmitters, respectively; analyzing one or more characteristics of thefiber segment; determining one or more parameters of the at least twodifferent optical carriers; and assigning a wavelength spectrum to eachof the at least two different optical carriers according to the one ormore analyzed fiber segment characteristics and the one or moredetermined optical carrier parameters.

b(ii). The method of claim a(ii), further comprising, after the step ofassigning, multiplexing the at least two different optical carriers tothe fiber segment according to the respective assigned wavelengthspectra.

c(ii). The method of claim a(ii), wherein the at least two differentoptical carriers include two or more of an analog signal, an intensitymodulated direct detection signal, a differential modulated signal, anda coherent signal.

d(ii). The method of claim a(ii), wherein the fiber segmentcharacteristics include one or more of fiber type, fiber length,implementation of amplification and/or loss devices, implementation ofwavelength filters or splitters, and fiber distribution networktopology.

e(ii). The method of claim a(ii), wherein the optical carrier parametersinclude one or more of individual carrier optical power levels,aggregate carrier power, number of optical carriers, signal wavelength,wavelength spacing among carriers, modulation format, modulationbandwidth, carrier configurability, channel coding/decoding,polarization multiplexing, forward error correction, and carriertenability.

f(ii). The method of claim a(ii), wherein the step of assigningcomprises the substeps of: first, placing fixed wavelength opticalsignals along a wavelength spectrum; second, place substantially robustoptical signals having relatively high noise tolerance closely adjacentthe fixed wavelength optical signals along the wavelength spectrum; andthird, place optical signals having relatively higher signal to noiseratios within areas of relatively low noise along the wavelengthspectrum, such that the substantially robust optical signals arepositioned between the optical signals having relatively higher signalto noise ratios and the fixed wavelength optical signals.

g(ii). The method of claim f(ii), wherein the step of assigning furthercomprises the substep of calculating a noise level of placed signalsafter at least one of the first, second, and third substeps.

h(ii). The method of claim f(ii), wherein the fixed wavelength opticalsignals comprise analog optical signals.

i(ii). The method of claim f(ii), wherein the optical signals havingrelatively high noise tolerance comprise one or more of NRZ and QPSKoptical signals.

j(ii). The method of claim f(ii), wherein the optical signals havingrelatively higher signal to noise ratios comprise one or more of PAM4,PAM8, 16QAM, and 64QAM optical signals.

a(iii). An optical distribution center apparatus, comprising: an inputoptical interface for communication with an optical hub; an outputoptical interface for communication with one or more end user devicesconfigured to process optical signals; a wavelength filter forseparating a downstream heterogeneous optical signal from the inputoptical interface into a plurality of downstream homogenous opticalsignals; and a downstream optical switch for distributing the pluralityof downstream homogeneous optical signals from the wavelength filter tothe output optical interface in response to a first control signal fromthe optical hub.

b(iii). The apparatus of claim a(iii), wherein the wavelength filtercomprises at least one of a wavelength division multiplexing grating anda cyclic arrayed waveguide grating.

c(iii). The apparatus of claim a(iii), wherein the downstream opticalswitch is an N×N optical switch configured to associate particular onesof the plurality of downstream homogeneous optical signals withrespective ones of the one or more end user devices.

d(iii). The apparatus of claim a(iii), wherein the first control signalis received from an intelligent configuration unit disposed within theoptical hub.

e(iii). The apparatus of claim a(iii), further comprising: an upstreamoptical switch for distributing a plurality of upstream homogeneousoptical signals collected from the output optical interface in responseto a second control signal from the optical hub; and an optical combinerfor aggregating the distributed plurality of upstream homogenous opticalsignals into a heterogeneous upstream optical signal to the inputoptical interface.

f(iii). The apparatus of claim e(iii), wherein the optical combinercomprises at least one of a wavelength division multiplexing grating anda passive optical splitter.

g(iii). The apparatus of claim e(iii), wherein the upstream opticalswitch is an N×N optical switch.

h(iii). The apparatus of claim e(iii), wherein the second control signalis a counterpart command of the first control signal.

i(iii). The apparatus of claim e(iii), wherein the optical distributioncenter is configured to receive the first and second control signalsseparately from the input optical interface.

j(iii). The apparatus of claim e(iii), further comprising a hybrid fibercoaxial portion in communication with the output optical interface.

k(iii). The apparatus of claim e(iii), wherein the second control signalis received from an intelligent configuration unit disposed within theoptical hub.

a(iv). An optical access network, comprising: an optical hub includingat least one processor; a plurality of optical distribution centersconnected to the optical hub by a plurality of optical fiber segments,respectively; a plurality of geographic fiber node serving areas,wherein each fiber node serving area of the plurality of fiber nodeserving areas includes at least one optical distribution center of theplurality of optical distribution centers; a plurality of end points,wherein each end point of the plurality of end points is in operablecommunication with at least one optical distribution center; and apoint-to-point network provisioning system configured to (i) evaluateeach potential communication path over the plurality of optical fibersegments between a first end point and a second end point, and (ii)select an optimum fiber path based on predetermined path selectioncriteria.

b(iv). The network of claim a(iv), wherein the point-to-point networkprovisioning system is disposed within the optical hub.

c(iv). The network of claim a(iv), wherein the first and second endpoints are disposed within the optical access network.

d(iv). The network of claim a(iv), wherein the first end point isdisposed within the optical access network, and the second end point isdisposed within a second access network including a second hub.

e(iv). The network of claim d(iv), wherein the optimum fiber pathtraverses at least one regional network between the optical accessnetwork and the second access network.

f(iv). The network of claim e(iv), wherein the optimum fiber pathtraverses at least one backbone network between the optical accessnetwork and the second access network.

g(iv). The network of claim f(iv), wherein at least one backbone networkincludes a primary backbone network and a secondary backbone network,and wherein the potential communication paths include at least oneprimary fiber path through the primary backbone network and at least onesecondary fiber path through the secondary backbone network.

h(iv). The network of claim a(iv), wherein the point-to-point networkprovisioning system is further configured to select an optimum opticalcarrier to transmit along the optimum fiber path.

i(iv). The network of claim h(iv), wherein the point-to-point networkprovisioning system is further configured to transmit the selectedoptimum optical carrier along at least one fiber path containing asecond optical carrier of a different carrier type than the selectedoptimum optical carrier.

j(iv). The network of claim a(iv), wherein the selected optimum opticalcarrier comprises a coherent signal transmission, and the second opticalcarrier comprises a non-coherent signal transmission.

k(iv). The network of claim a(iv), further comprising at least onedatabase in operable communication with the point-to-point networkprovisioning system.

l(iv). The system of claim k(iv), wherein the at least one database isconfigured to index associations of all potential point-to-pointcommunication links between different pairs of end points among theplurality of end points.

a(v). A method of provisioning point-to-point communications between twoend points of a multi-end point optical network, comprising the stepsof:

indexing all end points of the optical network;

defining each potential point-to-point connection between the indexedend points;

determining a topological fiber path for each defined point-to-pointconnection, wherein each topological fiber path includes one or moreoptical fiber segments;

calculating available transmission wavelengths for each of the one ormore fiber segments;

selecting an optimum fiber path between the two end points based on thedetermined topological fiber path and the calculated availabletransmission wavelengths; and

provisioning a point-to-point communication link between the two endpoints along the selected optimum fiber path.

b(v). The method of claim a(v), wherein the step of determiningcomprises analyzing each topological fiber path against one or morenetwork performance requirements.

c(v). The method of claim b(v), wherein the one or more networkperformance requirements include one or more of bandwidth parameters,latency parameters, and noise parameters.

d(v). The method of claim a(v), wherein the step of determiningcomprises analyzing each topological fiber path to further determine aset of all nodes crossed along the respective fiber path and thecorresponding lengths of the one or more fiber segments traversed overthe respective fiber path.

e(v). The method of claim d(v), further comprising a step of filteringout each topological fiber path that does not meet predetermined fiberpath selection criteria.

f(v). The method of claim e(v), wherein the predetermined fiber pathselection criteria include a redundancy requirement.

g(v). The method of claim f(v), further comprising a step of located asecondary path that corresponds to the selected optimum fiber path.

h(v). The method of claim g(v), wherein the optimum fiber path isselected based on a high degree of orthogonality with the correspondingsecondary path.

Some embodiments involve the use of one or more electronic or computingdevices. Such devices typically include a processor or controller, suchas a general purpose central processing unit (CPU), a graphicsprocessing unit (GPU), a microcontroller, a reduced instruction setcomputer (RISC) processor, an application specific integrated circuit(ASIC), a programmable logic circuit (PLC), a field programmable gatearray (FPGA), a DSP device, and/or any other circuit or processorcapable of executing the functions described herein. The processesdescribed herein may be encoded as executable instructions embodied in acomputer readable medium, including, without limitation, a storagedevice and/or a memory device. Such instructions, when executed by aprocessor, cause the processor to perform at least a portion of themethods described herein. The above examples are exemplary only, andthus are not intended to limit in any way the definition and/or meaningof the term “processor.”

This written description uses examples to disclose the embodiments,including the best mode, and also to enable any person skilled in theart to practice the embodiments, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the disclosure is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal language of the claims.

What is claimed is:
 1. An optical access network, comprising: an opticalhub including at least one processor; a plurality of opticaldistribution centers connected to the optical hub by a plurality ofoptical fiber segments, respectively; a plurality of geographic fibernode serving areas, wherein each fiber node serving area of theplurality of fiber node serving areas includes at least one opticaldistribution center of the plurality of optical distribution centers; aplurality of end points, wherein each end point of the plurality of endpoints is in operable communication with at least one opticaldistribution center; and a point-to-point network provisioning systemconfigured to (i) evaluate each potential communication path over theplurality of optical fiber segments between a first end point and asecond end point, and (ii) select an optimum fiber path based onpredetermined path selection criteria including an impact of a relativeoptical power difference between a first optical carrier and a secondoptical carrier, wherein the first optical carrier is of a differentcarrier type than the second optical carrier.
 2. The network of claim 1,wherein the point-to-point network provisioning system is disposedwithin the optical hub.
 3. The network of claim 1, wherein the first andsecond end points are disposed within the optical access network.
 4. Thenetwork of claim 1, wherein the first end point is disposed within theoptical access network, and the second end point is disposed within asecond access network including a second hub.
 5. The network of claim 4,wherein the optimum fiber path traverses at least one regional networkbetween the optical access network and the second access network.
 6. Thenetwork of claim 5, wherein the optimum fiber path traverses at leastone backbone network between the optical access network and the secondaccess network.
 7. The network of claim 6, wherein at least one backbonenetwork includes a primary backbone network and a secondary backbonenetwork, and wherein the potential communication paths include at leastone primary fiber path through the primary backbone network and at leastone secondary fiber path through the secondary backbone network.
 8. Thenetwork of claim 1, wherein the point-to-point network provisioningsystem is further configured to select an optimum optical carrier totransmit along the optimum fiber path.
 9. The network of claim 8,wherein the point-to-point network provisioning system is furtherconfigured to transmit the selected optimum optical carrier along atleast one fiber path.
 10. The network of claim 9, wherein the selectedoptimum optical carrier comprises a coherent signal transmission, andthe second optical carrier comprises a non-coherent signal transmission.11. The network of claim 1, further comprising at least one database inoperable communication with the point-to-point network provisioningsystem.
 12. The system of claim 11, wherein the at least one database isconfigured to index associations of all potential point-to-pointcommunication links between different pairs of end points among theplurality of end points.
 13. A method of provisioning point-to-pointcommunications between two end points of a multi-end point opticalnetwork, comprising the steps of: indexing all end points of the opticalnetwork; defining each potential point-to-point connection between theindexed end points; determining a topological fiber path for eachdefined point-to-point connection, wherein each topological fiber pathincludes one or more optical fiber segments; calculating availabletransmission wavelengths for each of the one or more fiber segments;selecting an optimum fiber path between the two end points based on thedetermined topological fiber path and the calculated availabletransmission wavelengths; and provisioning a point-to-pointcommunication link between the two end points along the selected optimumfiber path, wherein a first wavelength of the available transmissionwavelengths comprises a coherent signal transmission, and a secondwavelength of the available transmission wavelengths comprises anon-coherent signal transmission.
 14. The method of claim 13, whereinthe step of determining comprises analyzing each topological fiber pathagainst one or more network performance requirements.
 15. The method ofclaim 14, wherein the one or more network performance requirementsinclude one or more of bandwidth parameters, latency parameters, andnoise parameters.
 16. The method of claim 13, wherein the step ofdetermining comprises analyzing each topological fiber path to furtherdetermine a set of all nodes crossed along the respective fiber path andthe corresponding lengths of the one or more fiber segments traversedover the respective fiber path.
 17. The method of claim 16, furthercomprising a step of filtering out each topological fiber path that doesnot meet predetermined fiber path selection criteria, wherein a peakpower of a particular segment of the one or more fiber segments isgreater than an allowable aggregate optical power of the particularsegment, and wherein the step of calculating further comprises adding toa cost factor of the particular fiber segment for an amount of the peakpower greater than the allowable aggregate optical power.
 18. The methodof claim 17, wherein the predetermined fiber path selection criteriainclude a redundancy requirement.
 19. The method of claim 18, furthercomprising a step of located a secondary path that corresponds to theselected optimum fiber path.
 20. The method of claim 19, wherein theoptimum fiber path is selected based on a high degree of orthogonalitywith the corresponding secondary path.